DIY LED driver for reef lighting

[Devs]

DEVS

Here's a dual CAT driver that will work. As it is, both channels are independent of each other. If you want to Parallel the channels, just connect the negative side of your LED string to both negative terminals on the board. I included pots with both chips for current adjustment. All you'd have to do is balance the load between the two CAT chips by adjusting each one to drive half your target current. For example- Say you want to drive a string of six XPG's to 1400 ma. Connect the string to one channel only, power-up, and adjust the current to 700ma. Now connect to the other channel only, power up, and adjust it for 700ma output. finally connect both channels and check the current, It should now be around your target of 1400ma.This design is nice because you're not forced to parallel drive if you don't need to, plus it has a 5V reg included for powering up the driver for situations where there is not a controller providing the 5V turn on signal or dimming signal. Feel free to mod it any way you like.

Much appreciated O2, but i've since been reading up on the LM3409, so I think I'm gonna be going with that.

Cheers

John

[sjnovakovich]

Holy Crap! I read some stuff that's over my head before, but this sent me straight to the bottom of the Marianas Trench!

[shirley386]

Question to Terahz (or anyone else that would happen to know):

If I have multiple I2C boards and want to dim them together (all at the same time); can I set the addresses the same on the I2C bus? Will they all recognize the coding from the Arduino and perform as if they were on a unique address or will there be a conflict?

[Porgy Bait]

Anybody know if any company has the Cat1401 chips in stock? Most say that they won't have any until Sept.

[Landsailor]

Octopart shows nothing, so you're probably stuck. Just go with a LM3409 design.

[Porgy Bait]

No you're right I'm stuck. I just received my Cat1401 triple boards yesterday from Itead.

[Landsailor]

Now, imagine that your business depended on those chips. :)

Send me the exact part number and I will check with some of our other sources. How many do you need?

[shirley386]

The correct part is CAT4101. Try here:

http://www.newark.com/jsp/search/productdetail.jsp?SKU=08R5264&CMP=AFC-OP&CMP=AFC-OP

[Porgy Bait]

Thanks Shirley just ordered them from Newark! Also thank you Landsailor. While I'm handing out thanks also Thank you DWZM, TheFishman65, terahz, and every body else that has a hand in this and all the many other DIY projects here at Reef Central. I've been a long time lurker here and over the years my interests have ebb and flowed in this hobby but I always know this is the place to go when I need help or good information.

[O2Surplus]

The correct part is CAT4101. Try here:

http://www.newark.com/jsp/search/productdetail.jsp?SKU=08R5264&CMP=AFC-OP&CMP=AFC-OP

Cool! It's nice to see that somebodies got them in stock. They've been sold out everywhere that I've looked. I lucked out though- a friend of mine, that wanted some drivers built, found some in France, and convinced the supplier to send them to me in the USA. I got 38 Cats for $76 :celeb3:

[Landsailor]

That doesn't surprise me. I buy reels of contacts from an authorized dealer in France for about 60% less than I can buy them in the US.

The stupid part is that they are made in the USA! How on earth, they can be manufactured here, shipped to and from Europe, and still cost 40% of where we used to buy them is beyond my comprehension.

[rrasco]

One word, Capitalism.

[jc286006]

if a 48v-150 watt-3.2amp power supply is used to supply the lm3409hv drivers and the leds have Vf of 3.4 each driver can run around 12-14 leds is this correct dont have a calculater handy right now? and if i run them at 750ma this power supply should be able to supply the volts and amps for up to 4 of the lm3409hv drivers is this correct?
i am a little confused about the whole volts milliamps watts amps thing i just want to make sure my thinking is correct
james

[terahz]

Question to Terahz (or anyone else that would happen to know):

If I have multiple I2C boards and want to dim them together (all at the same time); can I set the addresses the same on the I2C bus? Will they all recognize the coding from the Arduino and perform as if they were on a unique address or will there be a conflict?

It might work. I haven't tried it though, and from what I read it depends on the i2c client (the DAC in this case).

Anybody know if any company has the Cat1401 chips in stock? Most say that they won't have any until Sept.
http://www.findchips.com/avail?part=CAT4101


The stupid part is that they are made in the USA!
Even though OnSemi has factories in the US, I'd be really surprised if the CATs are indeed made in the USA.

if a 48v-150 watt-3.2amp power supply is used to supply the lm3409hv drivers and the leds have Vf of 3.4 each driver can run around 12-14 leds is this correct dont have a calculater handy right now? and if i run them at 750ma this power supply should be able to supply the volts and amps for up to 4 of the lm3409hv drivers is this correct?
i am a little confused about the whole volts milliamps watts amps thing i just want to make sure my thinking is correct
james
3.4V * 12-14 LEDs = 40.8V-47.6V, the 14 count is pushing it.

4 strings at 750ma will be 3A. I strongly advise against using a 3.2A PSU under a constant load of 3A. My personal limit would be about 2.5A. In other words, I wouldn't put more than 3 strings on it.

To sum it up, I would put at most 3 strings of at most 13 LEDs (with 3.4Vf) on this power supply (assuming it can actually regulate the specs you list under load)

[jc286006]

thanks terahz i didnt have a calculater handy when i posted this but you have answered my question !!!! its better to be under the max to be safe!!! but i was just trying to get my head straight about how the volts amps works in trying to figure out how many drivers and how many power supplies you needfor a build
thanks for clearing it up for me
james

[Landsailor]

Even though OnSemi has factories in the US, I'd be really surprised if the CATs are indeed made in the USA.


I didn't state that they were. I was referring to the multiple reels of 4,000 contacts that I buy a few times a year.

[terahz]

I didn't state that they were. I was referring to the multiple reels of 4,000 contacts that I buy a few times a year.
My apologies, misunderstood you.

[Porgy Bait]

Thanks terahz for the link to FindChips. Its like Google for chips. I will be using it for future projects. Man I wish they had it back when I went to school it would have made life a bit easier.

[MaLi]

Greetings,

does anyone have some extra pcb for TeraHz schematic (Arduino I2C commanded) ?
PM please.

cheers,
MaLi

[Landsailor]

A couple of spreadsheet related questions for the LM3409.

How do I pick the Output Voltage of these 10W chips when the Vf is listed as "10-12"? It would be great if I could use one of these 24VDC power supplies we have laying around the shop.

What's a desired Switching frequency?

Thanks,
Jason

[Landsailor]

Double post deleted.

[Aqua@Home]

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

[O2Surplus]

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

Aqua@Home, use a 10k pot and 549ohm resistor with the CAT4101 and a 250kohm pot and .1mf cap with the LM3409. I've attached a couple of diagrams for you, good luck with your drivers.

[Aqua@Home]

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success :(

[rrasco]

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success :(

I built a circuit I found online, but it didn't work very well. Any reason you don't want to use something like an Arduino? That makes it a lot funner and adds a ton of capability. I wanted the pot controlled generator for a temp setup, everything is now run off an Arduino and I couldn't be happier.

This is the circuit I used: http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

http://www.youtube.com/watch?v=YnLa-hY74q4

[Aqua@Home]

I built a circuit I found online, but it didn't work very well. Any reason you don't want to use something like an Arduino? That makes it a lot funner and adds a ton of capability. I wanted the pot controlled generator for a temp setup, everything is now run off an Arduino and I couldn't be happier.

This is the circuit I used: http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

http://www.youtube.com/watch?v=YnLa-hY74q4

I am a physics graduate and a big zero in programming :( :spin2: :headwally:

But I know electronics as my special subject was electronics :)

Hence was trying to make a circuit based PWM (analog) to dim the led through the cat4101.

[rrasco]

I guess I have the advantage of being a developer, but there are tons of resources here on RC that you have to help you program your controller. Once I had my LCD, temp sensor, and RTC working...I pulled code from some threads here and had my lights ramping up/down flawlessly within an hour. Not only was it fun, it's amazing watching them ramp down at night.

[ZenMastr1968]

Thanks DWZM.... I was trying to re-read the whole thread to figure out where things currently stand. Now I know :)

My Hydra has been itching for something more important to do for awhile and I had been saving up for a Cree retrofit for the BC29 I setup last year....since I now have the money and nanotuners isn't an option, I'm back onboard here.

I'm looking to build a 24 led array - not sure how many strands of which color yet . Have seen some good builds along this line and am still looking for a driver to fit my needs. I want to do sunrise /sunset dimming via Hydra (pwm), but want the leds to go completely off. I think I remember reading in this thread one of the designs could do that (I was told that meanwells could only go down to a certain point and then you had to kill the mains so I gave up that route). Is that still true and if so which design?


Sent from my LG-P999 using Tapatalk

Both of the chips mentioned above are capable of full shutdown via the PWM dimming input. In fact that's how I am running things on my tank. If you use terahz's LM3409 design make sure you get the latest version as earlier versions didn't shut down correctly when operating with analog dimming.

In your case it will probably come down to how many different strings you have and if their Vfs are similar. If you end up with lots of different colors at lots of different Vfs the CAT4101 is a pain because it's hard to tune a single DC supply to cover a wide range like that. So you might either have to use several DC supplies (not the end of the world) or use the LM3409 for some or all of your strings.

Thanks, I'll sort out my strings and/or colors and see where that "LEDs" me....:lol2:

Sent from my LG-P999 using Tapatalk


Ok, back from the depths of obivilion...

My stock lighting has Sh%%%%%t the bed recently and I've pulled the trigger on the rapid LED dimmable retro kit for the BC29. I know it has the meanwells in it - which I was against, but needed a kit that would get me light again as soon as possible and wasn't interested in trying to repair the PC fixture in my hood. I'm only planning on using the meanwells long enought to get a suitable driver from here built and operational....

With that said, as previously stated, I have a Hydra and want to do sunrise/sunset dimming. The kit is supposed to come with 12 RB Cree XT-E and 12 Cool White Cree XP-G. I'm sketchy as to how to figure out the needed voltages and/or strings - I think the RB XP-E should be run around 800mA and the CW XP-G around 1200mA, so that tells me I need at least 2 drivers (besides the fact that I would want to dim w vs b anyway) because of the current differences. Are there any other factors that effect this?

I'm not 100% sure what I'm asking, but where do I find the calculation infomation to figure out how many of the XP-E and how many XP-G can be in a given string and how many drivers I'd need for those strings?

TIA and another great job to all that have contributed to this project.

[TheFishMan65]

You will be fine with 12 one a string. You may want to stop here :)

The number maximum on a string is tricky. First start with the supply voltage 48 volts for the ELN (usually). Then you have to guess at the current you will be running them. Then go to the datasheet and see what voltage that corresponds to. The typical LEDs we have been dealing with will have a voltage drop of 3 to 3.9 volts (IIRC). So somewhere between 16 (48 / 3) and 12 (48 / 3.9)is the maximum.

You must meet the minimum voltage of the ELN (27 volts IIRC) so do not use less than 9 (27 / 3) and you will be safe.

[ZenMastr1968]

You will be fine with 12 one a string. You may want to stop here :)

The number maximum on a string is tricky. First start with the supply voltage 48 volts for the ELN (usually). Then you have to guess at the current you will be running them. Then go to the datasheet and see what voltage that corresponds to. The typical LEDs we have been dealing with will have a voltage drop of 3 to 3.9 volts (IIRC). So somewhere between 16 (48 / 3) and 12 (48 / 3.9)is the maximum.

You must meet the minimum voltage of the ELN (27 volts IIRC) so do not use less than 9 (27 / 3) and you will be safe.

Thanks FishMan - that is similar what I calcuated. I want to drop the meanwells and switch over to either the LM3409 or the Cat4101 drivers.

My equation went like this....
for whites: XR-G ~ 3.2V forward voltage at 1000mA
So 12*3.2 + .7 + .35 = 39.45 {i read somewhere to add in the additional drops}
that meant I'd need a 48 v supply to run that string.

for blues: XT-E ~ 3.1V forward voltage at 750mA
So 12*3.1 + .7 +.35 = 38.25
also a 48 volt supply

So if these numbers are close - which flavor driver would be better for this situation? I read that the cat worked better if the input closely matches the output, so would these be close enough to run both strings off the same power supply?? I suppose the blues could run with a higher current to more closely match the whites and dial down the 48V PS to 39V. I haven't looked at powers supplies yet, but is that too much of a drop??

Or would it be better to just use the LM chip and let them run at the amps I want them to???

Thoughts?

[O2Surplus]

Thanks FishMan - that is similar what I calcuated. I want to drop the meanwells and switch over to either the LM3409 or the Cat4101 drivers.

My equation went like this....
for whites: XR-G ~ 3.2V forward voltage at 1000mA
So 12*3.2 + .7 + .35 = 39.45 {i read somewhere to add in the additional drops}
that meant I'd need a 48 v supply to run that string.

for blues: XT-E ~ 3.1V forward voltage at 750mA
So 12*3.1 + .7 +.35 = 38.25
also a 48 volt supply

So if these numbers are close - which flavor driver would be better for this situation? I read that the cat worked better if the input closely matches the output, so would these be close enough to run both strings off the same power supply?? I suppose the blues could run with a higher current to more closely match the whites and dial down the 48V PS to 39V. I haven't looked at powers supplies yet, but is that too much of a drop??

Or would it be better to just use the LM chip and let them run at the amps I want them to???

Thoughts?


The CAT4101 chip is only rated for 25volts, so you'd be limited to 6-7 leds per string with that one. The LM3409 is rated for up to 42 volts IIRC and the LM3409HV can go as high as 75volts. The LM3409HV will be the best choice for driving long strings of leds. You can always go "overkill" with your design in respect to output current and then turn it down, using the Iadj pin and a pot, to suit your needs.

[ZenMastr1968]

The CAT4101 chip is only rated for 25volts, so you'd be limited to 6-7 leds per string with that one. The LM3409 is rated for up to 42 volts IIRC and the LM3409HV can go as high as 75volts. The LM3409HV will be the best choice for driving long strings of leds. You can always go "overkill" with your design in respect to output current and then turn it down, using the Iadj pin and a pot, to suit your needs.

That's what I was thinking, so I put though an order for 2 sets of the HV bom this afternoon. I know those are for 1amp, but I think that its only a few component changes to alter and I'm pretty sure I saw THz post a lower amp version somewhere in the thread - I'll have to keep looking for it.

One other question, what are the options for a 48v PS? I saw some single output mean well brand ones that were rated at 2 or 5 amps for about $45. Would that be a good choice?

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[O2Surplus]

One other question, what are the options for a 48v PS? I saw some single output mean well brand ones that were rated at 2 or 5 amps for about $45. Would that be a good choice?

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

Check FleaBay. You can find them new for around $60 for a 7 amp model. I found a couple of "gently used" units for $30 apiece. Just be patient and don't fall for the cheap prices advertised by suppliers from China. They advertise MeanWell, but they'll sell you a supply made by a company called MengWell and claim it's the same company. Genuine MeanWell supplies come from Taiwan.

[ZenMastr1968]

Thanks O2, it seems like a 5 or 7 amp supply would be overkill, but in the long run would that run cooler since it wouldn't be working as hard?

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[ZenMastr1968]

And given that line of thinking, would the HRP-300-48 be a good choice?

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[O2Surplus]

And given that line of thinking, would the HRP-300-48 be a good choice?



I couldn't find a listing for that part number,but this is what I use. It's slightly more powerful than the one you listed. Look for a MeanWell S-320-48. It's rated at 6.5 amps. I'm running 5 strings of 12 leds each @ 1000ma with no problems.

[ZenMastr1968]

I couldn't find a listing for that part number,but this is what I use. It's slightly more powerful than the one you listed. Look for a MeanWell S-320-48. It's rated at 6.5 amps. I'm running 5 strings of 12 leds each @ 1000ma with no problems.

This is the one I saw....
http://www.powergatellc.com/mean-well-hrp-300-48-power-supply.html

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[O2Surplus]

This is the one I saw....
http://www.powergatellc.com/mean-well-hrp-300-48-power-supply.html

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

That one will work just fine.

[ZenMastr1968]

That one will work just fine.

This sounds like the one you have.
http://www.powergatellc.com/mean-well-sp-320-48-power-supply.html

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[rrasco]

I'm curious if anyone has had an issue like I am having with one of my triple CAT4101 boards. I just noticed it yesterday, but it may have been like this for a few days, although it was working last week for sure. One of the boards is not powering its strings as high as it should be; only powering about 50%. I have four boards running, the other three are fine. Readings are consistent for PWM signals compared to the working boards. The 24v line is pulling around 17v where as the working boards are pulling about 22v. The line outs to the strings are consistent with these readinge. The wire to the non-working board is getting 22v, but when plugged into the board, only draws 17v. So I'm concluding it has been isolated to the board. I have also swapped the power cords to my fixtures to ensure it's not the fixture itself. Also the boards are in a locked enclosure, they should not have been exposed to anything.

Any ideas? I don't have a spare board to test at the moment, I accidentally fried my originals by hooking them up to the 12v bus instead of the 5v when testing. Oops.

[kcress]

The board is drawing enough to drop 5V across the supply wire.

[rrasco]

It was my fault. There was a weak connection to the 24v bus. When I disconnected it from the board I would get a normal voltage reading, but when there was a current draw the voltage would drop to the board. I eventually narrowed it down to the bus and corrected the connection. All is good now.

[O2Surplus]

I just bought (50) CAT4101's from Newark this week, so they sent me a voucher code good for 15% off future purchases through the end of July. They said I could share the code with whomever I wanted, so I'll post it here- as copied from their Email.


"The Voucher code is NEW2P and it can be used as many times as you would like through July 31 2012, feel free to share with whomever you would like"


*Discount applies to the first price-break quantities only. Discount cannot be combined with other offers, promotions, quantity discounts, or contract pricing. Contractual considerations with a small number of manufactures may reduce or prevent a voucher discount on selected items including test equipment; call us with questions relating to voucher exclusions. Non-catalog items are not subject to a voucher discount.

[Porgy Bait]

Ha I ordered 4 last week and they only gave me a 10% code.

[kcress]

Wow! With that price break you can now buy things at the same price that Digikey and Mouser charge all the time! LOL

But thanks for that code. Seriously.

Hey Porgy Bait: What was your code? Maybe we can see a pattern and figure out what the 50% one might be... Heck maybe we can figure out the 100% one!!

[rrasco]

I almost ordered a few this week thinking something was wrong with one of my cat4101 boards. I'm curious why these are in such high demand right now, when I bought mine in December I could of sworn they had thousands. I wonder who snatched them all up.

[O2Surplus]

Wow! With that price break you can now buy things at the same price that Digikey and Mouser charge all the time! LOL

But thanks for that code. Seriously.



Your welcome Kcress! I'd normally get them from Digikey or Mouser, but they're out of stock. I needed them in a hurry and Newark was the only distributor listing any. Even after paying for expedited shipping, my cost came to $2.99 for each chip, but I'm happy with that.

[shirley386]

terahz - I've got the parts ordered for your LM3409 driver with I2C dimming. Could you post a sketch snippet of the code you're using for dimming?

Thanks
Shirley

[ZenMastr1968]

terahz - I've got the parts ordered for your LM3409 driver with I2C dimming. Could you post a sketch snippet of the code you're using for dimming?

Thanks
Shirley

I too would like to see what's different about it..

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[ZenMastr1968]

Anyone have a couple extra of the latest LM boards? PM me if you do. Otherwise I'll send in an order tomorrow- got my parts in and want to get off these meanwells...

Sent from my LG G2x running EaglesBlood AOSP4.0.4 ICS with Tapatalk 2

[89Delta]

KRavEN,

I've downloaded both zip versions of your driver design and from the location on github, but I get error trying to open the eagle files. Says it's invalid data in file...any ideas??

Thanks

[shirley386]

I got all the parts to build several of Terahz's LM3409 I2C drivers and got one put together. I connected it to a Hydra with a sketch that searches for I2C devices. If found it so I felt good about that. I soldered up a string of 12 LEDS for a test run. I loaded a sketch that I thought would dim them to about 50% and connected the Hydra to the driver, power supply to the driver, and LED string to the driver. I powered everything on and WOW did they light up! I was surprised that they would be that bright at 50%. To further test it I changed the value of the dimmer and reloaded the sketch. No change, still very bright. No matter what value I enter they do the same thing. Then I unplugged everything and took the Hydra with the I2C connection, ground, and 5V off. The only things connected are the power supply, driver, and LEDs. Still does the same thing. I checked as best I could with a high power magnifier but I can't see a short anywhere.

Kinda mixed emotions; yes it works but it doesn't work right!

Any suggestions? I think tomorrow I'll just start over building another driver.

[89Delta]

Great thread everyone...with all of you contributing something I thought i'd throw it out and try to see if the LT3496 is a good candidate. If I read everything online correctly I can run 10x 3W LEDs @750mA across all three outputs the chip has using a 30V PS in conjunction with the LM2841 I believe. I know its meant for use in RGB applications but I thought WTH...

[shirley386]

Now I'm wondering if I've got the LM3409 on backwards. If I'm looking at the board with the heat sink away from me, the little dimple is on the top left side, on the side next to L1. I'm now noticing a small white dot on the silkscreen on the opposite corner. Should the dot on the chip line up with the dot on silkscreen?

Sorry to be a pain!

[89Delta]

Yes Shirley,

All chips have a tell-tale sign of where the correct alignment is for the chip or any other for that matter...lol. Call it a "cheat sheet".

Now I'm wondering if I've got the LM3409 on backwards. If I'm looking at the board with the heat sink away from me, the little dimple is on the top left side, on the side next to L1. I'm now noticing a small white dot on the silkscreen on the opposite corner. Should the dot on the chip line up with the dot on silkscreen?

Sorry to be a pain!

[noplay180]

How many drivers would i need to run 225 3 watt drivers are they dimable

[89Delta]

You would need 38 of the CAT4101 Drivers if you go that route or 13 triple drivers ....unsure of the LM3409HV though.

[terahz]

terahz - I've got the parts ordered for your LM3409 driver with I2C dimming. Could you post a sketch snippet of the code you're using for dimming?

The basic code for telling the driver to dim looks like this:


byte Program = 64; // Program command
byte Device = 96; // Driver Address
int value = 500; // (0-4095)

byte b1 = byte((value / 16));
byte b2 = byte(value % 16);

Wire.beginTransmission(Device);
Wire.write(Program);
Wire.write(b1);
Wire.write(b2 << 4);
Wire.endTransmission();


Then I unplugged everything and took the Hydra with the I2C connection, ground, and 5V off. The only things connected are the power supply, driver, and LEDs. Still does the same thing. I checked as best I could with a high power magnifier but I can't see a short anywhere.

Kinda mixed emotions; yes it works but it doesn't work right!

Any suggestions? I think tomorrow I'll just start over building another driver.

Check the voltage between C4 and R4 (pin 2 of the lm3409). It is likely that it is shorted to something high and overriding the DAC voltage.

Now I'm wondering if I've got the LM3409 on backwards. If I'm looking at the board with the heat sink away from me, the little dimple is on the top left side, on the side next to L1. I'm now noticing a small white dot on the silkscreen on the opposite corner. Should the dot on the chip line up with the dot on silkscreen?

It is unlikely that you got it backwards and still have working LEDs.

[terahz]

How many drivers would i need to run 225 3 watt drivers are they dimable

Depends on the current you plan to drive them and if you're ok running strings in parallel.

If you drive the LEDs at around 700ma, you can easily put 3 parallel strings of 14-15 LEDs each per LM3409HV@2.1A (48V in). That will mean you need 5 drivers. Yes, they can dim the LEDs too.

for the CAT4101 drivers, that is about 32 ICs or about 11 tripple channel boards (if my math is right).

[ZenMastr1968]

Ok, could use a little help. I didn't find the lower amp LM3409 lists for THz's design, so I'm going to try to run through the spreadsheet myself. Can some one give me an indication of a good target for frequency in step 2? Up above that section it says Fsw should be between 100 - 1,00kHz. Is that the same frequency and is that 100 Hz or 100kHz to 1,000kHz (and isn't that 1mHz)???

[ZenMastr1968]

and as a follow up - what is Cout on THz's design? I don't see that referenced in the data sheet, but do see C2 on the output side going to ground - is that it??

[shirley386]

OK, I've built two working drivers. I built a "test string" of 6 XT-E CW and 6 XT-E RB. While it will certainly dim, it does not dim as low as I expected. With the minimum value in Terehz's sketch (16), it only dims to what I would call 50 - 60 %. I had hoped that it would dim down to almost nothing.

Any ideas?

[terahz]

Ok, could use a little help. I didn't find the lower amp LM3409 lists for THz's design, so I'm going to try to run through the spreadsheet myself. Can some one give me an indication of a good target for frequency in step 2? Up above that section it says Fsw should be between 100 - 1,00kHz. Is that the same frequency and is that 100 Hz or 100kHz to 1,000kHz (and isn't that 1mHz)???

If you don't want to get into details about the frequency, use 400kHz. It is what is used in the application notes.



and as a follow up - what is Cout on THz's design? I don't see that referenced in the data sheet, but do see C2 on the output side going to ground - is that it??

Yes, C2 is the output cap.

OK, I've built two working drivers. I built a "test string" of 6 XT-E CW and 6 XT-E RB. While it will certainly dim, it does not dim as low as I expected. With the minimum value in Terehz's sketch (16), it only dims to what I would call 50 - 60 %. I had hoped that it would dim down to almost nothing.

Any ideas?

Ok, few things here. Can you measure the voltage at the point between R4 and C4 for the highest and lowest values you can use (I assume when you use 15, the LEDs shut off?).

Do the same at the point between U3 and R6.

[shirley386]

Ok, few things here. Can you measure the voltage at the point between R4 and C4 for the highest and lowest values you can use (I assume when you use 15, the LEDs shut off?).

Do the same at the point between U3 and R6.

Lowest value that will allow lights to come on is 2
R4 - C4: .01
U3 - R6: .00

Highest value: 4095
R4 - C4: .08
U3 - R6: .31

These are the reading with the multimeter set on 20V. If I've done my math correctly then:

Lowest value that will allow lights to come on is 2
R4 - C4: .2 V
U3 - R6: .00 V

Highest value: 4095
R4 - C4: 1.6 V
U3 - R6: 6.2 V

[terahz]

Ok, I'm not sure how you compute the second values but I'll take your word for it. The U3-R6 value being 6.2V is strange because the max for the DAC is 5.5V... Are you sure you're feeding 5.0V to the board? I can't see how you'd get more than that at U3-R6.

1.6V at the highest value also seems a bit high, it should be more like 1.3V but that could be explained by lower tolerance resistors. If you want to get a perfect range, you'd have to adjust the values of R6/R7 divider to get a perfect 1.24V at the max range. However I have a feeling you're feeding a bit more than 5V to the board, which would translate in higher output voltage as well.

Either way, it looks like the circuit is operating pretty much as it should. You're supposed to get between 1.3V-0.1V at R4C4. That is the dimming range of LM3409.

Can you measuring the current though the LEDs at the two ends of the dimming range? The moment you hit 1.3V on R4C4, you should be at the maximum current you've built your board for. At the lowest dimming range, you should have only a few mA going through the LEDs.

If that is the case and it still feels like the LEDs are too bright at a few mA current, it is likely that your eyes are playing tricks on you and in fact they are dimmed way down.

[shirley386]

I'm computing it from the 20V setting on the multimeter: 20 * .31 = 6.2. I realize now that that is not correct as I checked the voltage from the Hydra and I didn't have to do the calcs.

I feeding it from a Hydra with the USB BUB powering it. I checked the voltage @ 5.02 V going from the Hydra to the driver.

I'm wondering if there is a short somewhere that is allowing some current from the 48 V power supply to "get involved". The LM3409 gets too hot to hold your finger on. That's about the only place I see a possibility for a short. I wonder if I fed too much solder into the hole on the back of the board and the "puddle" that I think is under the chip is shorting to a pin(s)? That thing is a witch with a capital b to solder!

[terahz]

What is the config of your board? How much current, how many LEDs etc?

If the LM3409 is to hot to touch, something is definitely wrong. Have you seen my video showing how I solder it?

If in fact you don't have to multiply the measured voltage, than 0.01V-0.08V is no good. Are the LEDs really bright?

You can try to remove the lm3409 by placing your board flat on a pan and on the stove. Just keep the heat at medium and watch the board, you will see it melt and you should be able to lift it with tweezers. Then try to resolver it.

Let us know how it goes.

[shirley386]

What is the config of your board? How much current, how many LEDs etc?

If the LM3409 is to hot to touch, something is definitely wrong. Have you seen my video showing how I solder it?

If in fact you don't have to multiply the measured voltage, than 0.01V-0.08V is no good. Are the LEDs really bright?

You can try to remove the lm3409 by placing your board flat on a pan and on the stove. Just keep the heat at medium and watch the board, you will see it melt and you should be able to lift it with tweezers. Then try to resolver it.

Let us know how it goes.

I'm using your BOM for the components. The string of LEDs consist of 6 XT-E CW & 6 XT-E RB.

I watched your video and you make it look easy. The problem I was having is holding it exactly in place to prevent the pins shifting to a neighboring pad. I finally clamped it with tweezers with one leg of the tweezers on top of the board holding the chip down and the other one on the bottom with an alligator clamp holding the tweezers down. Then I could gently nudge it until it looked like the legs were lined up correctly and started soldering and cleaning up with solder braid.

I'll try to cook one of the boards and see if I can get the chip off and redo it.

[terahz]

Ok, so you have built them for 1A and 48Vin. 12 XTs at 1A should require a bit less than 38V. You might want to add another 2 LEDs in there to reduce the load on the IC (since it has to regulate more than 10V down at 1A).

Again, measure the current that is going through the LED strings. Just break the LED circuit somewhere and with your multimeter in current mode, complete the circuit. If that is more than 1A (which might happen if something is shorted and the LEDs start drawing their max current) then you definitely want to redo the board. If it is at 1A, then at least you know the main part of the board is correct. Then you'll want to look at U2/U2 R6-R11 and C6 for shorts/bridges.

Also, I've had a board from china come shorted, so it is possible that the board is bad too.

Good luck.

[AHutch]

Hi folks. i could use some help with the lm3409 driver board. I built two boards based on Terahz's v0.7 design and used the components in the attached spreadsheet.

195732

The configuration consists of 9 XT-E LEDs in series, a single I2C driver board v0.7 and a 28v(27.65v actual) power supply.

Both boards seem to function fine at full on though the total LED current is lower than expected. I probably need a higher input voltage however i am happy with the lumens output at full on.

At the highest setting (4095), R4/C4 voltage is 1.242v and LED current is 300ma.
At the lowest setting (2), R4/C4 voltage is .130v and LED current is 100ma.

I see two problems:

First, based on previous comments it sounds like the LED current should be much lower than 100ma at the lowest setting.

Second, on the lowest setting the lm3409 gets very hot :eek1: to the touch. At the highest setting, I feel no heat from any component on the board.

I tweaked my design last minute and the Roff and Cin values aren't ideal based on the configuration. Could this cause problems with heat when the lm3409 needs to switch at a higher frequency?

I used a 28v supply that was "free" and a 32v supply would probably allow me to reach a higher current. Could the lower voltage be the cause?

I don't see any visible shorts on the board and I find it strange that both boards are exhibiting the same symptoms.

Any help would be greatly appreciated... Thanks

[terahz]

I have no idea how the board operates if Vin is lower than the LED voltage.

I'd just remove one of the 9 LEDs and try again. Otherwise try with the 32V PSU.

Other than that, the r4c5 voltage ranges are pretty much spot on, so my bet is on the lower Vin. Given that this is a switching regulator, it is probably going crazy trying to drive the LEDs.

EDIT: the Datasheet suggests that the regulator stops switching in the case you have, and the output voltage starts dropping with the input voltage. That is probably why you see only 300mA at max.

[AHutch]

Thanks Terahz. I took out one of the LEDs. On the highest setting, the LED current increased to 980ma without excessive heat from the lm3409c. On the lowest setting, 108ma with heat.

So... let me ask what I should have asked in my first post. Should the lm3409 even get warm in a conservative configuration like this one?

[terahz]

I've only tested the board with a big load (48Vin, 14 LEDs at 1.5A), and the IC got just a little warm. The mosfet was doing just fine with the chunky heatsink. I never really let it on the dimmest setting for a very long time, nor did I think it would be hotter than on higher current.

I definitely wouldn't expect it to be 'too hot to touch'.

I would also think that the minimum current would be lower... I can't exactly remember how low I got when I measured things. What is the ripple current of the inductor that you have?

[BeanAnimal]

First though, here is my version of the LM3409 design:

http://code.google.com/p/hpled/source/browse/#svn%2Ftrunk%2Flm3409


I went and built some drivers and a spreadsheet to calculate the required values (no idea this thread existed). Checking google for existing calculators for LM3409 values, I (oddly) found my way back to my own home forum...

In any case, it looks like I wasted 2 hours building a spreadsheet that has already been built....

I did however find a slight error in the spreadsheet that DWZ has posted.

The Forumula in cell B29 should be changed to read
=B7+B23/2

instead of
=B30+B23/2

The ILmax value in step 3 should be derived from the user chosen Iled value. The Iled value in step 4 is the Iled current that results from the Rsense choice.

:) have fun...

(and don't mind me, the LED hater... I was never here)

Cell B24 references

[BeanAnimal]

If the LM3409 is to hot to touch, something is definitely wrong.

The datasheet indicates that PFET with a Qg > 30 can cause excesive heating and that moving the Cin from VIN-VCC to VCC-CSN can help...

Just a thought.

[terahz]

Hey Bean, thanks for the fix on the spreadsheet and the note about the PFET. I couldn't find a good high voltage fet that has <30 Qg. The one I'm using is 33 and my Fsw is about 320kHz, so I'm just at the border :).

AHutch, I just did a quick test with one of my boards and on the lowest setting (3 in my case) I get about 11mA current through 7 XPGs with 24V psu (on a board with parts for 48Vin and 1A max current).
What parts are you using for Roff (R5), Coff(C5) and PFET (Q1) ?

[BeanAnimal]

Being new to HPLED drivers and having no real world design experience, I have no idea what the rammifications of switching frequency and ripple have on the end result. Sadly, these are the variables that must be fiddled with to optimize a buck regulator like this.

Lower Qg means higher Rds-on and the datasheet indicates that there is a trade-off but (again) I am not sure of the rammifications on either side of the trade, other than the high Qg and heating.


So, in the end it may be worth trying to move the Cin cap to the alternate position (away from Vin) to accomodate the high Qg and low Rds-on

[BeanAnimal]

Vishay has a few lower Qg offerings in HV packages

IRF9520PBF
100V
Qg= 18nC
Rds-on = 600mOhm
6.8A

[terahz]

Initially I had a pfet with high Rds and low Qg and the fet was getting quite hot... I guess having higher Qg moves the heat to the IC, having higher Rds, makes the FET hotter. Now that I've added a heatsink to my board, it is probably better to have the FET take the heat.

The part I'm using is FQP27P06 with max Rds of 0.07Ohms and typ Qg of 33nC. It seems to work well for me. I guess doubling the Roff resistor will lower the switching frequency and reduce the load on the IC, so maybe that's another option...

The only downside of this IC, too many things to consider and trade off.

The CAT4101 is a simple alternative, but not as fun :D

[BeanAnimal]

My biggest gripe is the current sense.. Due to the topology, there is no way to make an adjustable output driver... You can't just toss a POT on the sense pins and adjust Imax as needed.

[terahz]

Not on the sense pins, but you can put a pot on the Iadj pin and adjust it that way.

[BeanAnimal]

LM3409 specs

■ 10,000:1 PWM Dimming Range
■ 250:1 Analog Dimming Range

It statest that both types of dimming can be done over the full range... but the specs above indicate that if you want high resolutiom then PWM needs to be used.


So I am a bit puzzled but may be reading the datasheet wrong... But when driven with a PWM signal it would appear that the input PWM signal is used to derive an output PWM signal and brightness is a function of that output PWM duty cycle. When EN is tied high (analog dimming) the LEDs are driven by a fixed PWM (based on component selection) and dimming of the LEDs is done by leaving the duty cycle as is but varying the output amplitude (voltage). Make sense, or am I not reading the theory of operation correctly?


It would also follow (if my assumption is right) reading the 250:1 spec, that that output voltage is derived from an onboard DAC and therefore only has ~250 steps from Vled to cutoff (the extra 6 missing steps likely the cutoff threshold area).

Anybody?

So if my assumptions are anwhere near correct, then connecting a 10, 12 or 16 bit DAC to do ANALOG dimming does not add resolution, as it is fixed at 250 steps and in fact the only way to get higer resolution is to drive a PWM signal from a 10, 12 or 16 bit source.


The next question being... with a PWM signal present on the EN pin, can the ADJ pin stil lbe used to drive down the overall amplitude, regardless of the PWM input. That is lets say that the driver is built for 1000mA and PWM, does lowering the voltage to the ADJ pin act as a MAXIMUM current adjuster? Looking at the block diagram it appears that it may.

[BeanAnimal]

So i am still missing some details with, but I am partly correct (albiet partly wrong):


Here is a link to an article from National describing the topic and partly specific to the LM3409.
http://powerelectronics.com/images/DesignFeatures_1-1110.pdf

of note is the color shift related to analog diming, though at low outout levels, analog is more efficient than PWM. A tradeoff, but in our case, spectral shift may not be a good thing.

So... I suspect I am going back to the drawing board and going to use PWM instead of analog. That still leaves me with the problem of being able to trim the maximum current for a given design, unless of course it can be Iadjusted down.

[kcress]

Yo Bean! It's very confusing so I have no doubt you're not clear on this.

Here's the main confusion issue:

A lot of drivers, like Meanwells, have versions of drivers that can be dimmed by analog then they have some versions that are PWM. In their PWM versions they just take in your PWM signal and average it into the controller which runs just exactly the same as the analog version. The average the PWM to give themselves an analog signal internally that is the controller reference.

Then you have other controllers that are PWM and the PWM signal is actually ANDed with the current driver's output drive signal. When the PWM is zero it flat shuts-off the output. PWM = 0% = ZERO output current.

PWM = 100% = No interference with the controlled output.

PWM = any other value is the output OFF then current controlled to the drivers full current limit.


Now, the 3409 is special. It has an analog input that sets the controllers operating point. Then it has another input that will gate off the output driver.

This is why the analog input can only dim the output over a smaller range than the PWM.

[terahz]

While I never intended to use 4000+ steps for dimming, I absolutely see finer steps than 250:1 on the analog range. Unfortunately it doesn't look like it is linear. From 1000-1001 (dac step), I get about 0.25mA increase in current. At the lower range there is pretty much no difference between, say 50 and 120 (dac steps). I get an increase of about 0.020mA from 50 to 150...

The PDF you linked kind of supports that it isn't limited to 250 steps on the analog side, but rather to 0-248mV across Rsns. Now, I assume internally it is just an analog scale, rather than going from analog to digital in the logic unit and back out to analog.

We'd need a scope to verify this, but I really doubt Vout is PWMed. I think it is constant voltage, constant current (with slight ripple). But I could be wrong.

Regarding color shifting, I'm not sure that is a problem. Especially since we don't know at what current are the colors are measured by Cree. My guess would be 350mA, since that's pretty much their standard current (for XP series anyway). Also, for me it feels like the LEDs become warmer when they are at the dimmest levels, which would also be similar to the color shift of the rising or setting sun (at least I'd like to think that way :D ) which is what I'm trying to get with the dimming anyway.

At the end of the day, as long as PWM is not used for setting the maximum current, I think it doesn't really matter for the 1-2hrs of dimming we do a day. I do, however, have a problem with setting the max using PWM... the fact that we don't 'see' the on/off cycle, doesn't mean that other organisms don't mind it. No science to back this up, just me.

To answer your question, yes, you can have a 0-1.24V voltage or just a pot on Iadj while PWMing the EN pin. I think it is just an on/off switch for the IC so it should be independent from the analog adjustment.

[BeanAnimal]

Yo Bean! It's very confusing so I have no doubt you're not clear on this.

Here's the main confusion issue:

A lot of drivers, like Meanwells, have versions of drivers that can be dimmed by analog then they have some versions that are PWM. In their PWM versions they just take in your PWM signal and average it into the controller which runs just exactly the same as the analog version. Right... I get that part and for the most part get the difference in topology between a buck converter with a PWM output and one that only chops the duty cycle on the current (analog).

Now, the 3409 is special. It has an analog input that sets the controllers operating point. Then it has another input that will gate off the output driver. I gathered that, but am not clear if both can be used at the same time. That is, build the basic driver for 1000mA max and use the analog adj with a trimmer to set the real world max to 900mA (or some other value) so that the string can NOT be overdriven by mistake via the software, etc.

This is why the analog input can only dim the output over a smaller range than the PWM. It is my understanding from the datasheet that both methods can dim over the FULL range, it just a question of resolution.

[BeanAnimal]

While I never intended to use 4000+ steps for dimming, I absolutely see finer steps than 250:1 on the analog range. Unfortunately it doesn't look like it is linear. From 1000-1001 (dac step), I get about 0.25mA increase in current. At the lower range there is pretty much no difference between, say 50 and 120 (dac steps). I get an increase of about 0.020mA from 50 to 150... Interesting, the low end problems are mentioned in the datasheet, but in the context that they are only slightly non linear. I would imagine that it depends on the frequency as well.

The PDF you linked kind of supports that it isn't limited to 250 steps on the analog side, but rather to 0-248mV across Rsns. Now, I assume internally it is just an analog scale, rather than going from analog to digital in the logic unit and back out to analog. I would imagine the input to the logic unit was a DAC, and thus the 250 steps. Maybe worth an email to National.

We'd need a scope to verify this, but I really doubt Vout is PWMed. I think it is constant voltage, constant current (with slight ripple). But I could be wrong. The way I read it and the way the plots in the datasheet appear, the output type depends on the mode of the regulator (as dictated by the status of EN and IADJ).

The
adjustable current sense threshold provides the capability to
amplitude (analog) dim the LED current over the full range
and the fast output enable/disable function allows for high
frequency PWM dimming using no external components.


In other words, the driver acts like a true current source with variable current, or can drive the leds via PWM (or appearnatly a combination of both.


At the end of the day, as long as PWM is not used for setting the maximum current, I think it doesn't really matter for the 1-2hrs of dimming we do a day. I do, however, have a problem with setting the max using PWM... the fact that we don't 'see' the on/off cycle, doesn't mean that other organisms don't mind it. No science to back this up, just me. My concern is also the organisms and their possible ability to sense or see the switching frequency, though the 60Hz flicker of fluorescents does not appear to be a problem.

My reasons for building the dimming drivers are only partly sunrise/sunset. I had hoped to use them to be able to color tune or color shift the fixture throughout the day, or permanently.

To answer your question, yes, you can have a 0-1.24V voltage or just a pot on Iadj while PWMing the EN pin. I think it is just an on/off switch for the IC so it should be independent from the analog adjustment. That is kind of what I read as well. That said, if it is an "on off" switch, then the output is switched on and off as well, with the only averaging being done by the inductor, more indication that in PWM in mode, the OUTPUT is PWM as well.

Thoughts?

[BeanAnimal]

Not super relevant, as the app note is for driving directly from AC mains without a vreg and ripple smoothing. Interesting though:

http://www.ti.com/lit/ug/snvu109/snvu109.pdf

[O2Surplus]

I don't have a full understanding of the operating principles behind the LM3409, but I can tell you this- It appears from the drivers that I've built that Analog dimming can be used in conjunction with PWM dimming at the same time. I built my drivers to output 3,000ma at 52 volts, but I'm able to dial down the current to 2,000ma to safely drive a particular BridgeLux led array. I followed the diagram in the spec sheet and connected a 250k ohm trimmer pot to the Iadj pin. I use it to dial in the maximum current and use the PWM signal from my arduino to dim from there.

[BeanAnimal]

That is pretty much what I was after... so I can continue with my project using this driver :)

Still very curious about the output waveform

[terahz]

I would imagine the input to the logic unit was a DAC, and thus the 250 steps. Maybe worth an email to National.

Page 9 of the datasheet has a diagram of the peak current control circuit. To me it looks like a simple comparator that turns on/off an input of the logic unit. Nothing more than that:
"The voltage across RSNS (VSNS) is compared to the adjustable current sense threshold (VCST) and Q1 is turned off when VSNS exceeds VCST..."

The Iadj voltage just changes where that comparator turns off.

I did sent TI an email about the 250:1 range, so I'll report back when they answer.


In other words, the driver acts like a true current source with variable current, or can drive the leds via PWM (or appearnatly a combination of both.


Yep, that's how I understand it as well.


My reasons for building the dimming drivers are only partly sunrise/sunset. I had hoped to use them to be able to color tune or color shift the fixture throughout the day, or permanently.

Yep, that is quite useful. I'm building my new fixture with all kinds of colored LEDs, so it should be fun :).


That is kind of what I read as well. That said, if it is an "on off" switch, then the output is switched on and off as well, with the only averaging being done by the inductor, more indication that in PWM in mode, the OUTPUT is PWM as well.

Thoughts?
Absolutely, if you are PWMing the EN pin, the output is indeed PWM, unlike the Meanwells as kcress described earlier.

...

'bout time I get a proper scope, anyone heard of OWON? The owon sds7102 looks really tempting with that 10Meg sample memory...

[kcress]

Lets see a lot has gone on here today.

1)This is why the analog input can only dim the output over a smaller range than the PWM.

It is my understanding from the datasheet that both methods can dim over the FULL range, it just a question of resolution.

You're correct. My choice of wording for that sentence was not the best. By range I meant the range of dimming values(10,000:1) not the overall range of brightness .

2) 3409: Yes the analog input can set the MAX and the PWM can apply to that set current.

3) It's very easy to see 256 steps of dimming in a tank. 512 would probably be very hard to see. I'm running 1024 and can see no steps what-so-ever.

4) I would not hesitate to run PWM at a frequency greater than 100Hz having no concern with the wildlife. There's no reason I can think of for them to have a higher frequency eyeball than us. They have the same brain/muscle/physical response limitations and likely the same functional need for integration to allow seeing poor light. But that's just my opinion.

5) tera; I've NEVER heard of Owon. I have heard of Rigol and have been considering the Rigol DS1102E.

My problem is that I need an isolated scope for at least half of my work. I have a Tektronix that is but the numbskulls at Tek have ignored that genre of scopes now for a decade. Instead they are wasting their time on scopes that I see selling for more than half a million dollars each. :headwallblue:

[dannytt]

Why no one use zetex led driver? I use it. I use it zxld1362/zxld1366 for under 1A application. If u want turn or dim the led driver the only method is use pwm. zetex led driver is very easy to design and use. If u wand driver 12 led in series by 60V dc u only need 1 zxld1366, 1 coil, 2 caps and 1 current sense resistor. The pcb can be very small and easy soldering them.....

[BeanAnimal]

I have old tektronix 2235, or 2213, honestly can't remeber if it is 60 or 100 meg. I don't use it very often. I would love storage scope but just can't justify the cost.

[BeanAnimal]

Why no one use zetex led driver? I use it. I use it zxld1362/zxld1366 for under 1A application. If u want turn or dim the led driver the only method is use pwm. zetex led driver is very easy to design and use. If u wand driver 12 led in series by 60V dc u only need 1 zxld1366, 1 coil, 2 caps and 1 current sense resistor. The pcb can be very small and easy soldering them.....

The ZXLD1370 or newer ZXLD1371 appear similar to the lm3409, but I have not fully read the datasheets.

[dannytt]

The ZXLD1370 or newer ZXLD1371 appear similar to the lm3409, but I have not fully read the datasheets.

ZXLD 1362/ZXLD1366 has internal MOSFET, and ZXLD1370/ZXLD1371 need extrnal add a MOSFET. if u need a led driver 1A or under zxld1362/zxld1366 is enough, but if u need driver over 1A then ZXLD 1370/ZXLD1371.

long long times ago i use national lm3404..... but it current sense is hard to find. so i choose zxld1362/zxld1366.....

[terahz]

5) tera; I've NEVER heard of Owon. I have heard of Rigol and have been considering the Rigol DS1102E.

My problem is that I need an isolated scope for at least half of my work. I have a Tektronix that is but the numbskulls at Tek have ignored that genre of scopes now for a decade. Instead they are wasting their time on scopes that I see selling for more than half a million dollars each. :headwallblue:

Yeah, the Rigol is quite popular but the owon is not much more expensive, yet it has a huge screen+resolution and much better hardware from what I read (real 1g/s even at 10M memory). Then there are the Hantek DSO5062B/Tekway DST1062B which can be hacked into 200MHz 1Gs scopes (they run linux and I've even seen pictures of people running xfce on them :) ). All of these are in the $400-$500 range.



I have old tektronix 2235, or 2213, honestly can't remeber if it is 60 or 100 meg. I don't use it very often. I would love storage scope but just can't justify the cost.


Justifying 400 bucks in this hobby isn't very hard :)

[BeanAnimal]

$400 = 20 cases of cheap beer or 10 cases of craft beer....

Honestly, I don't often find use for a scope often. At one point I had visions of building high power SS and tube amps, and purchased the scope for that reason. I have piles of massive high voltage/current ONSEMI power transistors for a huge sub amp build, but never got around to doing it :)

My plan here is to use something like the NXP 16 channel driver to drive the PWM inputs on the LM3409 -OR- the NXP PWM output through a simple rc filter or opamp to drive the analog input of the LM3409.

[dannytt]

just for diy led driver not worth buy a scope.....

[terahz]

You guys are no fun :) Of course it is not worth it to buy a scope because of an led driver.:)

Bean, 16 lm3409s can handle e LOT of LEDs, are you changing the lights for the tank and the house? :)

[BeanAnimal]

Nope, just two smallish fixtures :)

It is more about building something modular and playing around with drivers than about optimizing a solution for a specific outcome. In fact, not all of the channels will be used, likely only 5 per fixture.

As you likely know, I am far from being an LED proponent. The emitters are becoming more efficient and spectral choices becoming more abundant.

I am fairly certain that a large portion of the "DIY" and many of the commercial fixtures are pretty lousy with regard to spectral output and their ability to sustain a broad range of SPS, Clams, etc.

I am however ready to give them a whirl, but only if I can control the spectral output, both to attempt to get acceptable life support AND to satisfy my eye. To date, I seen very few LED tanks that appeal to me with regard to the color of light they cast. I aim to build a fixture that pleases both myself AND the coral :)

[terahz]

I hope you get the color spectrum you're after. I'm sure with enough different LEDs you can, it is just a matter if, is the complexity worth it.

Do you judge the spectrum visually or do you have some nice toys for that?

I'm also after better colors. I've gathered quite a few color LEDs to mix with the usual NW/CW/B/RB combo to see if I can get some better colors.


EDIT: Oh, forgot to say that TI replied to me saying that I should go to the Community Support Forums, so I guess I'll be posting my question there.

[BeanAnimal]

I hope you get the color spectrum you're after. I'm sure with enough different LEDs you can, it is just a matter if, is the complexity worth it.I hope as well. My first inclination was to order a pile of LEDs and experiment with combinations until I found what I wanted and then build the fixture with the ratios and drive currents found. In the end I honestly don't feel like dealing with a drawn out process so I am going to build the spectral adjustment into the fixture. Moreover, this is likely 1 time and like it or dump it adventure. I just don't have the drive (no pun) to fiddle with LEDs when there are so many more interesting things I can find to do with my time and money. Not knocking anybody who finds it interesting, but it is one rabbit hole that I am not that interested in climbing down. I have maybe a dozen (or more) unfinished micro and similar projects laying around that need attention.

Do you judge the spectrum visually or do you have some nice toys for that? I have some toys (a fairly high end tristimulus colorimeter), but it is not well suited to the task at hand as it is more suited to relating color to the CIE colorspace as opposed to a spectrophotometer that measures true spectral output. That is, with some baseline calibration, it could give a decent idea of the relative spectral output from a known source to an unknown source. In the end, way too much work and a spectrophotometer (or spectroradiometer) is way too expensive.

Short answer, If the coral DOES somehow grow, then tweaking so that my eyes are happy is all that counts :)

EDIT: Oh, forgot to say that TI replied to me saying that I should go to the Community Support Forums, so I guess I'll be posting my question there. Typical, instead of getting an answer from an engineer, they pawn you off on a group of nitwits who want to be engineers but can't (Microsoft MVPs and the MS community forums anybody?).

I will call the local Allied rep tomorrow and get him to get us an answer. The guy knows I am a hobbyist, but treats me no different than a volume manufacturing customer. I am using them more and more due to the wonderful customer service.

[kcress]

Tera; Definitely let us know which scope you get and what you think of it.

What scope do you have now?

And I can't remember and can't find what question you are positing with TI. What was it?

[BeanAnimal]

I think the question was asking for technical clarification of the dimming resolution between PWM and ANALOG... something an engineer should answer, not a self educated nitwit (like most of us) in a community forum.

I do like this LM3409, kinda magical... not bacon magical, but close.

[terahz]

Not knocking anybody who finds it interesting, but it is one rabbit hole that I am not that interested in climbing down. I have maybe a dozen (or more) unfinished micro and similar projects laying around that need attention.

I have a beaglebone with 7" touch LCD sitting on my desk, waiting to become my next controller... now that I got my openbeam parts to build my fixture I should be able to finish it and move to one of the many things on my desk :).


Short answer, If the coral DOES somehow grow, then tweaking so that my eyes are happy is all that counts :)

I think you'd have a hard time finding HP LEDs that don't grow coral. Making the eyes happy is a different story :)



I will call the local Allied rep tomorrow and get him to get us an answer. The guy knows I am a hobbyist, but treats me no different than a volume manufacturing customer. I am using them more and more due to the wonderful customer service.
Great, let us know. I'm also interested to know if I wasted my time with a 12bit dac.

I will try to go to a friend this weekend with a scope an maybe get some photos of the output, just for fun :)

[terahz]

Tera; Definitely let us know which scope you get and what you think of it.

What scope do you have now?

And I can't remember and can't find what question you are positing with TI. What was it?
Sure. Reading about cheap-o DSOs in the last few days still points me to the OWON sds7102 so IF I get one, it is going to be the owon.

It doesn't really qualify as one, but I have a DSO nano :).

I think the question was asking for technical clarification of the dimming resolution between PWM and ANALOG... something an engineer should answer, not a self educated nitwit (like most of us) in a community forum.


Yep, I asked them if they can clarify how the analog dimming works and how they got the 250:1 number in the datasheet, and they sent me to the community forums :).

[AHutch]

Terahz - I should be using the following components:

Roff 7.32K
Coff 470pF
Q1 FQP27P06

The excel spreadsheet i posted in my original post has all of the components that i selected.

EE is not my forte but i borrowed a scope from a friend anyway to play around a bit.

If I'm using it correctly, PGATE/Coff frequency is ~2.5MHz with the DAC at the lowest setting and it looks like a 50% duty cycle. That is, Ton and Toff appear to be at 200ns each.

From the lm3409 spec: "In practice, switching frequencies higher than 1MHz may be difficult to obtain due to gate drive limitations, high input voltage, and thermal considerations."

Is Toff to short requiring a higher switching frequency? Either that or maybe i did a poor job soldering the back side of the lm3409 and it can't dump to the heat into the board.

[terahz]

AHutch, the .xls you linked says your max current is 2A, but the XTEs' max current is 1.5A. You might want to put a .151 Rsns instead.

Also, the 8 LEDs at max current will probably put the driver in dropout mode, because they have a Vfw of 27.2V and your psu is 27.65V? At lower currents you should be good though.

If we plug your numbers in the datasheet calculation, you should be at about 450kHz. Try going to 11K resistor (if you don't have one, maybe stack two R7s(30K) with one R8(100K)). That should lower the Fsw to about 300kHz(250kHz) and hopefully reduce the load on the chip.

I still can't explain why it would get hotter at lower currents though.

Also, I think you want to measure Coff and LED+ (Vo) to get the proper Toff.

[AHutch]

Terahz, i failed to fill in the average LED current in cell B7 but it doesn't look like it's used in an calculations. The calculated 1058mA which is close to what i am able to hit with 7 XT-E LEDs. Running 8 or 9 does limit the total current to under 1A due to the Vin of 27.65v.

One question: the switching frequency is expected to change as you change the output of the DAC, correct? I assumed the switch frequency in the spreadsheet would be the switching frequency required to limit the total LED current to the desired value. In my case, this is 1A.

Lowering the DAC output voltage to further reduce the LED current will require an increase in the switching frequency, correct?

Thanks again!

[terahz]

One question: the switching frequency is expected to change as you change the output of the DAC, correct? I assumed the switch frequency in the spreadsheet would be the switching frequency required to limit the total LED current to the desired value. In my case, this is 1A.

Lowering the DAC output voltage to further reduce the LED current will require an increase in the switching frequency, correct?

(one of the EEs feel free to slap me if what I'm about to say is garbage)
While this is correct, it is a not directly because of the change in current, but the change of forward voltage of the LEDs as a result of the changed current. The switching frequency depends on the input and output voltages of the driver (apart from the roff/coff combo).

In your case, of 7 LEDs, at 100mA, they should have ~ 18.55Vfw. With 27.8Vin you need to have a 3.5K Roff and 470pF Coff to get to 2.5MHz. And my guess would be, at that frequency it is likely that the chip gets on the hot side :).

With the same 7 LEDs at 1A, Vfw is ~ 22.05V and that should give you a Fsw of 760kHz with your 7400 Roff.

So again, my recommendation is to get a higher value Roff. A 16.5K Roff, which is what I use for my 1A drivers, should give you a Fsw range of 340kHz-540kHz (high current - low current). That should make the driver happy.

[shirley386]

Terahz - thanks for the tip on putting the boards on the stove to remove the chip; worked like a charm.

I've got two "working" drivers now. They drive a string of 14 XTEs that I have been burning as a test. I have them on a 12 hours cycle with a 2 hour ramp up and ramp down. The chip gets very hot, to hot to hold your finger on. I actually thought it would burn up or unsolder itself before it got through a whole cycle. It gets hottest at the lower settings. I set it ramp from 1 to 4095 and same coming down. The lights never do get very dim. Even at the lowest setting that will light them they appear to be about 50 - 60%. Also, at the lowest settings they will begin to flicker. I can hold a pencil on the chip and the flicker stops.

I originally thought I had a short somewhere on the chip but both boards do the same thing. I'm thinking now that I must have a wrong component(s) somewhere. I went by your 1 amp BOM and the power supply is right at 48V. I tried to check the current but I can't get my meter to work on amps.

I guess I'll double check the components and if I can't find the problem I don't know what else to do.

[kcress]

Switching loses are the major loss in these setups. The higher the frequency the greater the loses, the hotter the chips get. Anything over 1Mhz should be avoided - like the plague.

[terahz]

shirley, have you soldered the bottom of the chip (I assume by chip you mean U1)? It sounds like you maybe haven't, and by pressing with the pencil, you ground the chip properly?

Also, does the chip heat up right away or does it take a while? Can you also take a temperature reading somehow? If it peaks at something less than, say 150F, it is fine to leave alone. 200F is probably fine too, though pushing it. The IC has thermal protection, so it will shut itself off when it hits 320F and go back on at around 290F. I surely hope you're not getting that high!

I'm not certain why this is happening, I haven't put mine in "production" yet, as I'm working on the actual LEDs array, but from the various several minutes of running while I've done testing, I never noticed the lm3409 getting too hot to touch. Admittedly, I've never done 'load' testing on the lowest stetting...

I'll try to replicate what you guys are getting and see what I can find. Manwhile, shirley, you can read up on measuring current with a big resistor with your multimeter in voltage mode. I think even here on reef central kcress has explained it a few times,

[terahz]

Switching loses are the major loss in these setups. The higher the frequency the greater the loses, the hotter the chips get. Anything over 1Mhz should be avoided - like the plague.

Hmm, I think this will be a problem for people with long arrays, because the LEDs we use can go down to 2.5Vfw and in shirley's case that would make the total Vo only 35V. On a 48V psu that will be a 800kHz frequency. On the same setup at 1A, the total Vo is 44V and Fsw is only 145kHz.

[shirley386]

Yes, I soldered the back of the chip. I measured it with a digital thermometer @ 141. In the process, I allowed the thermometer to short something out and it all went dark. Now I'm down to one driver.

[terahz]

Oops, that sux. Sorry.

However, 141F is fine, given that the thermal shutdown is at 320F.

I've had 7 XPGs running at 18mA (lowest DAC setting) for about 1hr now. Vin is 25V, Vfw is 18.37V. Once I put my pinky on the IC, I don't feel any heat for the fist 4 seconds, then 3 seconds later it is too hot to hold. I used my computer's fan controller to measure about 120F, but I don't know how accurate that is given the tiny chip and the clunky probes the controller has.

If I turn Vin up to 26V, the chip becomes considerable hotter. Going to Vin 24, takes about 15 seconds of touch to become really hot, but I wouldn't call it too hot to hold.

At 22Vin the chip is barely over ambient temperature.

So, If switching frequency can be correlated to temperature, it looks like this:

400kHz - slightly above ambient.
450kHz - gets to "too hot to touch" after about 7-10 seconds (110F is probably a good measure of where 'too hot to touch' starts)
500kHz - too hot to touch in about 3 seconds.

That would support what you guys are observing as well.

Still, I wouldn't be worried about it at 150F. It might be worth tweaking Roff and Coff to get a lower frequency for some people.

If you are worried about the heat, add a second Coff(C5) on top of the current one (in parallel) and I'm sure that will make a big difference.

Don't forget to report back guys.

[shirley386]

Still, I wouldn't be worried about it at 150F. It might be worth tweaking Roff and Coff to get a lower frequency for some people.

If you are worried about the heat, add a second Coff(C5) on top of the current one (in parallel) and I'm sure that will make a big difference.

Don't forget to report back guys.

Would that address the issue of it not dimming down?

I'd like it to dim down to "moonlight" or "I can't be sure it's on"

Thanks
Shirley

[terahz]

Shirley,

I don't know how to answer that as I'm not sure what you expect in terms of dimming down. I still don't know how low in terms of current your drivers get. Assuming the circuit is running correctly, you are as low as it gets. Changing the frequency will not make a difference either way though. Maybe you can tell us the voltage between L+ and L-? That might give us a idea how low your current is at the lowest setting.

I don't think you will be able to dim 14 XT LEDs to the level of 14 3mm LEDs if that is what you're after. Even at 12mA, the 7 LEDs I have are still enough to light up my "lab" (brightness adjusted to about what I see with my eyes, yes I know it depends on the monitor but it is as good as I can do for visual representation):

http://joro.geodar.com/images/uploads/leds_dimmed.jpg

If you need dimmer than that, you either have to PWM with something that supports 11bits+ of PWM to get in the microamps. (The analog dimmer certainly cannot get that resolution in the lowest points).

Or just get 5-10 cheap 3mm LEDs from anywhere and use them as moonlight. You can probably drive them directly from your micro.

Hope that helps.

[AHutch]

A Mastec power supply would certainly make things easier...

So I swapped out the 7.32k Roff for a 16.5k Roff and it changed a few things. For one, Iled dropped from 108mA to 38mA at the lowest DAC setting. The LEDs are considerably dimmer now on the lowest setting. Also, the chip is no longer too hot to touch at this setting. I don't have an accurate way to measure the temperature but lets just say it's no longer a concern. :)

I grabbed pics of a few traces on the lowest and highest settings.

LED - 7 XT-E
Vin - 27.55V
Roff - 16.5 kOhm
Coff - 470pF
L1 - 33uH
Rsense - .22Ohm
Cin - 2.2uF
Cout - 2.2 uF


Lowest setting:
DAC (2) 9mV
V R6R7 126mV
Vout 18.83V
Iled 38mA

PGate
http://s10.postimage.org/gxsrp9pll/pgate_low.jpg

RoffCoff
http://s16.postimage.org/6cap0otx1/Roff_Coff_low.jpg

Fsw appears to be about 750-800kHz at the lowest setting.

Highest setting:
DAC (4095) 5V
V R6R7 1.29V
Vout 23.19V
Iled 960mA

PGate
http://s10.postimage.org/i5gcscbfd/pgate_high.jpg

Fsw appears to be about 125-150kHz at the highest setting.

The Arduino's onboard voltage regulator stopped working before i could capture the Roff Coff trace on the highest setting. I will say that there is a lot of noise on the highest setting. The scope picked up voltage spikes at the same frequency on the 5V source line connected from the arduino to the driver.

[terahz]

A Mastec power supply would certainly make things easier...

The second channel on mine died 3 days after I got it... still haven't fixed it.


So I swapped out the 7.32k Roff for a 16.5k Roff and it changed a few things. For one, Iled dropped from 108mA to 38mA at the lowest DAC setting. The LEDs are considerably dimmer now on the lowest setting. Also, the chip is no longer too hot to touch at this setting. I don't have an accurate way to measure the temperature but lets just say it's no longer a concern. :)

Yay! Good news for Shirley as well. I guess I was wrong about the frequency not affecting the current.


Lowest setting:
DAC (2) 9mV
V R6R7 126mV
Vout 18.83V
Iled 38mA

That is really odd, how on earth is a voltage divider boosting the voltage of the dac?!

On a side note, I just measured the current for the first 300 steps of the dac and the strangest thing happened. The dimmest setting for me is actually at about 200 (245mV dac output, 65mV at the IC). Not sure why, but that gave me 11mA.

Can you try it on your build ? Are the LEDs getting brighter as you move from 5 to, say, 50?

Thanks for the photos! Can someone explain what they mean? :)

[shirley386]

So I swapped out the 7.32k Roff for a 16.5k Roff and it changed a few things. For one, Iled dropped from 108mA to 38mA at the lowest DAC setting. The LEDs are considerably dimmer now on the lowest setting. Also, the chip is no longer too hot to touch at this setting. I don't have an accurate way to measure the temperature but lets just say it's no longer a concern. :)

Now that sound promising! Can you see any difference in intensity at the highest setting?

[BeanAnimal]

http://joro.geodar.com/images/uploads/leds_dimmed.jpg




Hrmmm.... did you break into my house and take a picture of my bench?

http://www.reeflogix.com/images/rc/beananimals-lab.jpg

I just moved my stuff over to this corner to give her bacl the utility room... but in there I had almost the exact same shelf layout as yours with the equipment in the same places... kind of creepy.

[shirley386]

Well, I just looked and Roff is R5 and I've already got a 16.5k there. I've got some extra 30k that I used on R7. Would that be worth a try or do you think it would just smoke the whole board! :headwally:

[terahz]

Hrmmm.... did you break into my house and take a picture of my bench?
<snip>
I just moved my stuff over to this corner to give her bacl the utility room... but in there I had almost the exact same shelf layout as yours with the equipment in the same places... kind of creepy.
Haha, that's crazy. I promise to put a scope under that bench meter eventually :)

Well, I just looked and Roff is R5 and I've already got a 16.5k there. I've got some extra 30k that I used on R7. Would that be worth a try or do you think it would just smoke the whole board! :headwally:

Shirley,
I really hope you don't smoke the board :). Yeah, I already knew you had 16.5K for Roff, that's why I suggested adding a second Coff (C5) on top of the current one. The frequency is affected both by Roff(R5) and Coff(C5). Since your resistor is already 16500, you can double up on the capacitor. If you just solder a second on top of the first one, that will give you the same result.

[shirley386]

Shirley,
I really hope you don't smoke the board :). Yeah, I already knew you had 16.5K for Roff, that's why I suggested adding a second Coff (C5) on top of the current one. The frequency is affected both by Roff(R5) and Coff(C5). Since your resistor is already 16500, you can double up on the capacitor. If you just solder a second on top of the first one, that will give you the same result.[/QUOTE]

I'll give it a shot. Nothing more to lose at this point.

[shirley386]

terahz - I stacked another cap as you suggested. I don't think the chip gets quite as hot as it did but it's still to hot to hold my finger on. The flickering at low setting has stopped though. It it still pretty bright as the lowest setting but probably not as bright as it was. Also, at max power it does not seem to be as bright as it was. I think that just reduced the brightness across the board.

In a effort to make sure that I had not ordered (or was sent) the wrong components, I got my big magnifier with the little "bifocal" spot on it, opened the blinds so the light would come in and managed to read the numbers on the resistors. I then found this site to decode them:

http://www.hobby-hour.com/electronics/smdcalc.php

(Hope it's alright to post that here)

Here's what I found:

For R6 the BOM calls for 91K ohms but the Mouser number listed is for 91 ohms.
For R7 the BOM calls for 30K ohms but the Mouser number listed is for 30 ohms.

I ordered them according to the Mouser number in the BOM spreadsheet. What do you think would be the result if I swapped these two resistors for the values that you have listed?

[terahz]

Shirley, good to hear the flickering has stopped. As for brightness, I think that's just what it will be. These LEDs are fairly bright (that's kind of the point), so it is hard to really dim them down with analog voltage.

Maybe some high precision PWM chip (like the PCA9685PW, as BeanAnimal suggested) will do better job at it. The data sheet suggests that it can handle up to ~13bits of accuracy with PWM, so it should be able to dim the LEDs down to 0.25mA vs the current ~25mA we get.

Regarding the LEDs, R6 and R7 are a simple voltage divider. In general it shouldn't matter much what their value is, it is the ratio that is important. However, I seem to remember the high resistance causing some problems at some point for the dac... hmm. I'm also running with 91 and 30, so I think you're good there.

I guess if you want to use what you have, you can PWM the EN pin (remove U2 and put PWM on the top right pin (the one who's trace goes between C4 and C5/R5 and ends in the middle of U1). But as I said before, I'd just get a handful of cheap LEDs and create your a moon light that way.

[nyquist]

So, I setup a driver like DWZM's, and here is my schematic:
http://img12.imageshack.us/img12/9223/driverboostschematic.png
I am just trying to get it to work without an actual PWM source for now, so I have a switch hooked up to the enable pin


I have tried the above using between 7 through 13 LEDs as the load. What happens is this:
(V1 = voltage across 1 ohm resistor; Vled = voltage across all the LEDs when on)

7 LEDs: V1 = 106mV, Vled = 23V (just under 3.3V per LED)
8 LEDs: V1 = 85.6mV, Vled = 25.6V
9 LEDs: V1 = 73.4mV, Vled = 28V
10 LEDs: V1 = 66.5mV, Vled = 30.5V
11 LEDs: V1 = 60.5mV, Vled = 33V
12 LEDs: V1 = 55mV, Vled = 35.6V
13 LEDs: V1 = 51mV, Vled =37.9V (just under 2.9V per LED)


So as I increase the number of LEDs, the current goes down and accordingly the voltage drop per LED goes down. Am I clearly missing something?

Why isn't my constant current driver supplying constant current? (I also setup two independent circuits the same way, both behave the same, so I am quite sure I didn't just set something up wrong, unless my schematic is wrong) Anyone have any insight for me? It would be greatly appreciated :)

[terahz]

Shirley, Bean and others, I've ordered a 12bit PWM chip to give it a try with the lm3409s. I'll let you guys know how that works. It should be able to give linear 4000+ steps at up to 1MHz.

[kcress]

12b = nut case..
Why not 16bits!
No! no! 24bits!!

[shirley386]

Shirley, Bean and others, I've ordered a 12bit PWM chip to give it a try with the lm3409s. I'll let you guys know how that works. It should be able to give linear 4000+ steps at up to 1MHz.

I did the PWM mod that you mentioned. This looks much more promising. It really dims now. I'll build a few more and test them. Also less components to solder!

It still started to flicker at the highest setting. I could hold the eraser end of a pencil on the chip and it stopped. When I took the pencil off it had begun to melt the rubber eraser. I was able to turn the power supply down a little to make it stop flickering without noticing any difference in intensity. I think the flicker must be a part of the thermal shutdown.

[terahz]

12b = nut case..
Why not 16bits!
No! no! 24bits!!

Heh, this time I wasn't looking for 12b, just trying to get higher 8 bit and that was the first one that I saw so I bought it :). But 16mil steps sounds like fun too :D

I did the PWM mod that you mentioned. This looks much more promising. It really dims now. I'll build a few more and test them. Also less components to solder!

http://www.reefcentral.com/forums/images/icons/icon14.gif


It still started to flicker at the highest setting. I could hold the eraser end of a pencil on the chip and it stopped. When I took the pencil off it had begun to melt the rubber eraser. I was able to turn the power supply down a little to make it stop flickering without noticing any difference in intensity. I think the flicker must be a part of the thermal shutdown.

You might be right there. Either way it is good to lower the PSU to as close as possible to the LEDs Vfw + ~0.5V. It is more efficient that way.

[shirley386]

terahz - I think I remember a few pages back you had used an ethernet cable to power your LED string(s). How is that working out? I was thinking about that too and looked up the specs on Cat5 cable and I think the current was about 500 mA. Other people have mentioned that it might not be a good idea as Cat5 is intended for data, not power. I'd like to get your experience.

[terahz]

No problem running cheap ethernet on mine for a couple of years now.

[89Delta]

Have read through this thread and am very impressed with everyone's work on the various drivers. I was thinking of trying my own build using the AL8805 LED Driver. Has anyone had any experience with these at all?

[cnbridge]

I have a question about multiple strings of leds. After reading this thread, I have decided to go with the cat4101 board with separate pwm. I want to connect multiple strings with different voltages to the same power supply. Each driver board will have the same leds. Can I use something like this http://www.ebay.com/itm/4-5-24V-0-93-20V-2A-DC-DC-Converter-Step-Down-Buck-Module-Voltmeter-/150843486243?pt=LH_DefaultDomain_0&hash=item231ef8f023#ht_1961wt_1180 to control the voltage to each driver?

[O2Surplus]

Can you give a better description of your proposed led layout with the number of Cat4101's and the type of leds that you plan to run? Depending on that info, there may be a better way to go about laying things out.
The DC/DC step-down convertor that you linked has some specs that seem suspicious. They list it as having a continuous 2 amp output, but it's only rated at 20 watts total output. Simple Ohm's law says 2 amps X 10volts = 20 watts. That leaves you only 10 volts for your leds, so your strings could only comprise 3 leds. In order to run 6 leds per string, you'd need 20 volts @ 1 amp. Simple math doesn't lie, and a $9 a pop for the dc/dc convertors, your money may be better spent buying more 24 supplies and skipping the dc/dc convertors all together.

[cnbridge]

Can you give a better description of your proposed led layout with the number of Cat4101's and the type of leds that you plan to run? Depending on that info, there may be a better way to go about laying things out.
The DC/DC step-down convertor that you linked has some specs that seem suspicious. They list it as having a continuous 2 amp output, but it's only rated at 20 watts total output. Simple Ohm's law says 2 amps X 10volts = 20 watts. That leaves you only 10 volts for your leds, so your strings could only comprise 3 leds. In order to run 6 leds per string, you'd need 20 volts @ 1 amp. Simple math doesn't lie, and a $9 a pop for the dc/dc convertors, your money may be better spent buying more 24 supplies and skipping the dc/dc convertors all together.

I am trying to utilize my existing power supply(generic 24v 6.4a) keeping everything simple. On one power supply I would like to run a string of 6 cree white xpg, a string of 6 blue xpe, a string of 4 green xpe, and a string of 4 xpe red. Each string will have its own driver all driven at .7A. I've read that power supply needs to be close to the Vf of the led string not to overheat the cat4101. Of course I am not very knowledgeable on this topic and my current led setup was created following directions from the original led thread. Thanks for your assistance.

[O2Surplus]

I had some down time a work a few weeks back, so to fight the boredom I fired up my EAGLE software and created this.
It’s a 6 channel CAT4101 Led driver PCB with an ATMEGA328P-AU and a DS1307 RTC built in.
It also includes a 12volt /1.5 amp regulator for powering cooling fans ect.. and a 5volt reg to power the CAT’s and the microcontroller.
All the pins on the ATMEGA chip are broken out for use, just like an “off the shelf” arduino, so adding additional functionality is just a bit of extra wiring and coding.
The Board includes a FTDI connection for programming purposes and an I2C connection for expansion.
I chose to include 6 CAT4101’s since that’s the number of PWM outputs available on the ATMEGA chip.
The Micro-Controller portion of the board is thermally isolated from the rest of the PCB, as it sits in it’s own Polygon with just a small ground trace connecting it to the rest of the board.
The CAT4101 chips sit atop 3 large vias that will conduct heat to the bottom plane of the PCB and ultimately to a dedicated heat sink.
The CAT4101’s PWM inputs are brought out to a six pin female header, instead of being hard wired directly to the ATMEGA.
I designed it that way to keep my options open with respect to different PWM connection configurations.
Each CAT 4101’s current output is fully adjustable from around 50ma to 1000ma maximum by turning a 10k trimmer pot that’s soldered inline with a 549ohm resistor.
I built three of these to replace the current CAT4101’s that have been driving my leds for the last 2 years or so.
My current led lighting system is comprised of 90 “ancient” Cree XR-E Q5 leds driven in groups of 6 by 15 CAT4101’s.
I’m not very good at writing code for the arduino yet, but I plan to learn how, as I would like to configure each ATMEGA chip as a “slave” to a “Master controller” via I2C some time in the future.
For now each of the three driver/ controller PCB’s has been programmed to run independently, with varying or staggered “on/off” and “fade duration” times to simulate “sunrise/sunset”.
They’ve been running that way for the last two weeks and seem to be performing well.
Let me know what you guys think?

http://i861.photobucket.com/albums/ab172/kovawa/SmartyCATLEDDriver003.jpg

[jgwinner]

I had some down time a work a few weeks back, so to fight the boredom I fired up my EAGLE software and created this.
It’s a 6 channel CAT4101 Led driver PCB with an ATMEGA328P-AU and a DS1307 RTC built in.
Let me know what you guys think?



Very cool!

Would like to see it in your enclosure.

== John ==

[89Delta]

O2Surplus.....i've done something similar to your 6-channel controller. Mine is 4-Channels though currently as i'll be using an I2C 20x4 Display. It also has pH and ORP capability as well. For input i'll be using a ADC-Keypad. Here is what I have so far....

[O2Surplus]

O2Surplus.....i've done something similar to your 6-channel controller. Mine is 4-Channels though currently as i'll be using an I2C 20x4 Display. It also has pH and ORP capability as well. For input i'll be using a ADC-Keypad. Here is what I have so far....

Way cool! I was planning to use an I2C LCD and buttons too. I like your design, but I didn't add any more functions to mine for fear of making it overly complex. I figured that if I passed them out to a few friends, they could choose how many additional components or functionality to add for themselves. Since all the pins are broken out going from "mild" to "wild" with the arduino portion of the board is totally doable.

[89Delta]

I may need to re-think this design for use with an Ethernet shield and/or a Bluetooth Module. I'd rather try to incorporate what I can without going too high on stack-able shields to keep the enclosure as "thin" as I can.

[Landsailor]

Let me know what you guys think?

http://i861.photobucket.com/albums/ab172/kovawa/SmartyCATLEDDriver003.jpg

I think that is covered in awesome sauce, O2!

What was the cost per board?

[O2Surplus]

Here's what the PCB looks like in EAGLE. My eyes have begun to give me trouble, so I tried to avoid using any components smaller than the 1206 package, lol.

http://i861.photobucket.com/albums/ab172/kovawa/6UPSmartyCat-1.png

[kcress]

How'd you get a white board or is that a paper label?

[Landsailor]

How'd you get a white board or is that a paper label?

It looks like he just made a negative of the silkscreen layer.

[O2Surplus]

How'd you get a white board or is that a paper label?

Hey Kcress- I was getting bored with plain old "green" so I blew an another $10 for "white". I had the PCB's made at SeeedStudio, but I think that "white" is a fairly new color option for them, as I hadn't noticed it until recently.

[jerpa]

Okay I'm just beginning the long journey down this thread. Can anyone point me to the "final" version of the CAT4101 driver for a single channel? It is going to take me a day or two to read and digest this thread. Digesting mistakes only to find out later they are mistakes is time consuming. Any help would be appreciated.

[O2Surplus]

There is no "final" version of the CAT4101 based driver. There are plenty of designs posted in this thread that are correct for the people who designed them. This thread documents the evolution of many of them. If there's a particular design consideration that you need, just ask, and may be one of us will already have what you want.

[jerpa]

I found the answer to my questions a few pages later. I was merely confused for a bit. I'm still designing the whole fixture. I know what I want I just need to figure out how to build it. As far as a driver I want 12+ channels, although some will be left unused. I plan on dimming with an Arduino controlled PWM signal. I'm looking at 96-120 LED's. At least 8 colors, although I think that will increase. I still have to figure out the emitter half so the exact number of channels and LED's per channel is up in the air. I see no reason I wouldn't be able to accomplish this, I've just got to get through the rest of this thread to figure out how.

As an aside the wealth of knowledge in this thread is pretty remarkable, and I'm only ~20 pages in. It makes these things quite accessible for those with a limited knowledge of electronics, like me. Although by the end of my build I think my knowledge will be a little less limited.

[BeanAnimal]

Jerpa,


We can talk about your plans at the meeting. Do you have any electronics experience or is this you first project?


I have a oscope, soldering stations, bench supply, meters and other goodies like a stereo microscope and beer.

[O2Surplus]

:beer: I gotta agree, BEER does make any project more enjoyable.

[jerpa]

Basic high school electronics, a strong foundation in math, the ability to grasp things pretty quickly, and the naive belief that I can do/learn anything I put my mind to. That's all I'm working with. I'm currently brushing up on my electrical theory. Electronics for Dummies and Practical Electronics for Inventors are being read as we speak. Lol.

[BeanAnimal]

I have some electronics books you can borrow if you need (and likely dozens or more ebooks). If I remember, I will bring them to the meeting.

[terahz]

jerpa, and anyone else who's interesed, I highly recommend this FREE MIT class:
https://www.edx.org/courses/MITx/6.002x/2012_Fall/about

Don't let the prerequisites scare you.

[moncapitane]

jerpa, and anyone else who's interesed, I highly recommend this FREE MIT class:
https://www.edx.org/courses/MITx/6.002x/2012_Fall/about

Don't let the prerequisites scare you.

I am such a nerd. I just signed up for 3 of the classes on the page you provided. The electronics class looks alot like the one I took while I was an engineering student for the few semisters I was before I moved to networking but it will be nice to have a refresher.

[BeanAnimal]

Hell, I may even sign up for that class. As long as I have been fiddling with electronics, a well put together refresher or course is always welcome. The chem course looks interesting, I always like chem for the first week (until the math and balacing, etc start).


See you guys in school :)

[terahz]

moncapitane, just want to say that these are real classes with real homework and reading. 3 classes is almost like being fulltime student. Just saying :)

The electronics class is neat, it has been online for a while now, I've "attended" it but didn't really do the work (see above). I will try to this time.

Bean, that chem class does sound interesting, especially when you read the description.

Time for Edu forum? :D

[jerpa]

jerpa, and anyone else who's interesed, I highly recommend this FREE MIT class:
https://www.edx.org/courses/MITx/6.002x/2012_Fall/about

Don't let the prerequisites scare you.

That is really cool. I will be attending. I have all the prerequisites, unfortunately that was a decade ago. You know what they say about calculus, it is just like riding a bike, right?

Thanks for the info.

[davebar]

Hi,

I am going to order some parts from Mouser for the CAT4101 chip.

The Mouser part #(80-C1206C105M5R) Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 50volts 1uF X7R 20% is $.48 each.

I wanted to find out if the chip #(810-CGA5L3X7R1H105MS) Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 1206 1.0uF 50volts X7R 20% Soft Term @ $0.16 is interchangable.

Thanks

[O2Surplus]

Hi,

I am going to order some parts from Mouser for the CAT4101 chip.

The Mouser part #(80-C1206C105M5R) Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 50volts 1uF X7R 20% is $.48 each.

I wanted to find out if the chip #(810-CGA5L3X7R1H105MS) Multilayer Ceramic Capacitors (MLCC) - SMD/SMT 1206 1.0uF 50volts X7R 20% Soft Term @ $0.16 is interchangable.

Thanks

Davebar-

Go with the cheaper cap. $.48 is silly money. The cap is only there for smoothing out any voltage "ripple" that may be coming from the power supply. I've built tons of cat4101 drivers and it's never been much of an issue to worry about.

[BeanAnimal]

I have not looked at the caps in question...

But when choosing a filter cap, you should be mindful about its voltage rating, not oversizing it too far. That is, a 300V cap filter a 24V circuit is going to live a shorter life than a 36V cap on that same 24V circuit due to the ESR increasing (oxidization and electrolyte drying out) due to under voltage conditions. You should also (esp with electrolytic) pay attention to the mean lifetime ratings. In most cases, the longer lived caps cost more.

I have a few good PDFs on the subject somewhere and will see If I can dig them up.

[davebar]

I apreciate the input (O2Surplus and BeanAnimal)

The cheeper cap say it is the Product: for Automotive MLCCs. The more
expencive cap says it is the Product: for MLCCs Tin/Lead Termination.

The rest of the specs are the same.

That is what I wanted to know about interchangeable.
So the replies make me feel safe ordering the parts.

[davebar]

I have been having trouble getting the flux off of the cool white XP-G R5 stars I got from RapidLED. I have scraped and used 90% methanol but I still get the polluting flux in the puddles that makes it verry difficult to soder the wire to the pads.

Is their a better way to clean up these stars?

[moncapitane]

moncapitane, just want to say that these are real classes with real homework and reading. 3 classes is almost like being fulltime student. Just saying :)

The electronics class is neat, it has been online for a while now, I've "attended" it but didn't really do the work (see above). I will try to this time.

Bean, that chem class does sound interesting, especially when you read the description.

Time for Edu forum? :D

The two programming classes shouldn't be too bad as I have a computer background and do some minor programming. Most of that information will not be new to be. An edu forum might be a good idea. I am for sure looking forward to the electronics class. I took one in college when I was an Engineering student so some of it isn't going to be new, just a refresher as well.

[shirley386]

I ordered some boards for the 3 channel CAT4101 drivers with separate dimming channels. I have since decided to use LM3409 drivers so I have a few of the CAT4101 boards if anyone wants some. Shoot me a PM.

[shark boy]

Does anyone have extra components for the Cat4104 drivers they would sell me?
I'm having trouble locating all the peices for a couple triple drivers from a single source.
Even parts for a single triple would work for now.
I tried Mouser and Digi-key but they are out of something on the list.
Please LMK,
shark boy

[khoff]

I'm hoping someone can help me out with this problem. Here's a summary of my system:

I'm running 3 CAT4101 driver boards, 8 chips total, 900ma ea, 56 Cree LED's.

I'm driving 2 PWM channels for blue/white control with an arduino mega.

All of this worked great for 6 months or so, until I added a couple "opto-isolated" relay boards this last week... Now, every time a relay contact makes or breaks, and my LED's are supposed to be off (the first 4 hours of my workday), i get a momentary flicker of both blue and white channels.

I thought the relays would be optically isolated from the arduino, but it seems I'm picking up some noise from somewhere. Should decoupling caps be installed somewhere? The only commonality between the relay board and the CAT4101 drivers are the 5V supply and GND (sourced from the Arduino), and the outputs both sourcing from the Arduino itself.

Also, should I run pulldown resistors on the PWM signal outputs from the arduino to the drivers? I say that, because if I physically touch the PWM wires when the channels are set to 0, I get a dim lighting of the LED's.

Thanks,
Kendall

[shark boy]

Does anyone have extra components for the Cat4101 drivers? I'm having problems finding the cat4101 chips.

Shurly someone out here has some extras
shark boy

[shark boy]

Got all my parts and put together my first cat4101 x3 pwm driver.
Soldering was easy.
Thank you shirley386 for the boards and thanks to O2Surplus for the rest of the parts.

shark boy

[zoaracer]

Hi,

i got hold of NCP3066 IC's as LED driver's for my DIY LED, i was looking into buck mode just to get more PWM resolution,

have any of you have used it in buck mode ?? let me know the BOM if you have..

i see a lot of guys have successfully used it in Boost mode..


Regards
Zoaracer

[zoaracer]

bump


:)

[rye_84]

Correct me if I am wrong on this, but the cat4101 accepts a 5v pwm signal in order to determine the brightness of the LED. While the apex outputs a 10v signal. If I remember right there was a circuit that someone had created in order to fix this change. Does anyone know where that is? Also, with the apex being able to output 4 signals/module can I connect multiple drivers to each output or would I need 1 channel for every driver? Is there anyone who is using the apex to control a cat4101?

Thanks

[Iceman13579]

Great advice, I envy you tech savvy guys out there

[nick7777]

Any suggestions on which driver would be the easiest to assemble for an amateur, as i am wanting to run around 12 3w LED's on each driver. thanks in advance.

[zeroinverse]

RapidLED quick connect LEDs with ELN60-48 drivers. Either D or P versions depending if you have a analog or PWM dimming control signals for your reef controller.

If no controller, then get D version and use a potentiometer to control dimming amount. RapidLEd has those too.

[nick7777]

i meant for building a driver..

[TheFishMan65]

Nick,

I think the CAT requires the fewest calculation, but it is surface mount easy but ...

[O2Surplus]

i meant for building a driver..

The CAT4101 is the easiest to build. If you need some PCB's just ask. I've got plenty to spare and I'm sure some of the other CAT4101 lovers on this forum will have some extras as well.

[nick7777]

i tried sending a PM but it told me i needed ten posts... any tips or walkthroughs would be awesome, i am an avid DIY'er but this will be my first electrical project(that isn't on anything with an engine) on another note i did download a zip file for the cat4101. just waiting for the software to read it to finish downloading.

[nick7777]

could you give me a price on the pcb. also how many LED's can this driver handle. thanks in advance.

[dallasg]

hi,
which would be the best schematic/design to use with the CAT4101?
i am going to be adventurous and make my own led light unit
tx

[O2Surplus]

hi,
which would be the best schematic/design to use with the CAT4101?
i am going to be adventurous and make my own led light unit
tx

Here's one that I built a lot of. It works really well and you're welcome to use it as is, or modify it how ever you please. I do recommend adding a heat sink to any design that you choose though, as the CAT4101 can get quite hot if it's input voltage vs. output voltage is not kept as close as possible. Here's a photo of slightly different version ( the build files for the one that I've attached use surface mount diodes for power indication and PWM channel isolation) Both designs feature on board 12V and 5V regulators for powering cooling fans, an Arduino ect.. There's even a jumper to power the driver board in cases where a PWM controller is not being used.
You'll need EAGLE to view the files. If you don't already have the EAGLE software it's available here for free. Just download the "Freeware" version-
http://www.cadsoftusa.com/downloads/?language=en

http://i861.photobucket.com/albums/ab172/kovawa/044.jpg

[dallasg]

thanks, thats champion of you, all credit will go to you on my build etc, and i will send you the link when i start

[nick7777]

sent you an email Fishman.

[TheFishMan65]

oops posted in the wrong thread ), but since I did I guess I will say I got the email

[speeddemon1891]

First let me say hello and thank you to all the people contributing to this thread. I have been a member a long time just never posted. The information and work being done here is amazing.

Ive been going through this thread for a long time. I am now unsure of how I should proceed.

I want to build drivers for 24 3w leds. I would like 3 drivers with each one powering 12 leds up to 1000ma. The problem is getting boards to build the drivers since it's such a small quantity and which driver would be best? I do not have much experience with smt components but I'm not worried about it. Any help would be greatly appreciated.

Thanks.

[O2Surplus]

First let me say hello and thank you to all the people contributing to this thread. I have been a member a long time just never posted. The information and work being done here is amazing.

Ive been going through this thread for a long time. I am now unsure of how I should proceed.

I want to build drivers for 24 3w leds. I would like 3 drivers with each one powering 12 leds up to 1000ma. The problem is getting boards to build the drivers since it's such a small quantity and which driver would be best? I do not have much experience with smt components but I'm not worried about it. Any help would be greatly appreciated.

Thanks.

Take a look at the MeanWell LDD series of led drivers. The LDD-1000H would work perfectly for your application. They're available for purchase for around $5 each so, from a performance standpoint, they're more economical than a comparable DIY effort. There's a big thread on them here- http://reefcentral.com/forums/showthread.php?t=2222702 There's been a few different Pcb's designed to mount the driver, and many members are ordering batches, so there's bound to be somebody on this forum that may share a few with you.

[speeddemon1891]

Thanks for the info O2.
Time for a lot more reading.

[Terminatermule]

Hey O2,

Great work on those boards, I was just learning/bashing around eagle to build my own when I found your thread, I have not studied the board closely yet but I was wondering what the total cost was, including the run from seeed

Thanks in advance for the reply, I look forward to reading this thread now, some really great work on here.

Cheers Glenn

[O2Surplus]

Hey O2,

Great work on those boards, I was just learning/bashing around eagle to build my own when I found your thread, I have not studied the board closely yet but I was wondering what the total cost was, including the run from seeed

Thanks in advance for the reply, I look forward to reading this thread now, some really great work on here.

Cheers Glenn

It's been a while since I built any more drivers using the CAT4101, but IIRC each 4 up Driver cost me < $40 to build. The Cat chips still cost $3-$4 each, so I'd recommend using the newer Meanwell LDD drivers instead. They offer superior performance to the CAT4101 for about the same amount of $$.
If you're really set on using the CAT 4101- send me a PM. I've got quite a few bare PcB's leftover that could use a new home.

[der_wille_zur_macht]

As far as I am concerned the LDD has invalidated the cost advantage of DIY'ing drivers unless you need features it doesn't have (i.e. more than 1A). DIY'd drivers are still a great pursuit from a hobby/interest perspective but they're probably not vastly cheaper any more.

[O2Surplus]

As far as I am concerned the LDD has invalidated the cost advantage of DIY'ing drivers unless you need features it doesn't have (i.e. more than 1A). DIY'd drivers are still a great pursuit from a hobby/interest perspective but they're probably not vastly cheaper any more.

I wholeheartedly agree. Unless you need more than 1000ma, go with the LDD's. If you do need more than 1,000ma and want to DIY, go for a design using the LM3409.

[zachts]

the only other advantage I see to the DIY drivers over the LDD's is the ability to adjust current as well as have pwm for diming. good for fine tuning multiple colors if you want them to dim all at once and maintain a certain blended color, such as with Red and Green or other supplemental colors.

[der_wille_zur_macht]

Yeah, though I would potentially segregate that into controller functionality, vs. driver functionality. If a driver can take ANY signal to alter output, you can probably build a controller or a signal converter to do whatever you want with it.

Translating that into the real world, you could put a "front end" on the LDD that took any combination of signal formats you wished and dimmed the driver accordingly.

[CrazyEyes]

I posted in the wrong thread. And couldn't figure out how to delete.

[zachts]

Yeah, though I would potentially segregate that into controller functionality, vs. driver functionality. If a driver can take ANY signal to alter output, you can probably build a controller or a signal converter to do whatever you want with it.

Translating that into the real world, you could put a "front end" on the LDD that took any combination of signal formats you wished and dimmed the driver accordingly.

that's true, would be cleaner, I still live in a knob oriented world and haven't leaped into controller/arduino design or programming yet so I lean toward simplicity and somthing that a simple typhon could controll but would have more fine tuning ability for the over all color. the ideal "white" I'm playing with requires at least 5 separate LED spectrums to create the white look that I like, using knobs to dial it in seems faster to me as I want it to just behave as a single color......

I'm mainly thinking of and planning a two channel setup, main lights dim up/ down. moonlights dim up/down. with all the color tweaking taken care of at the driver level with good old simple knobs :)

which on the typhon or any similar already figured out DIY project controller (doesn't require me having to learn anything new to build) then leaves you with controll for sump LEDs or PWM fans/other devices, or a second bank of lights for Left to right dimming as well.....

there are some LEDs such as whites though that look differnt at different driver currents and to get consistent color over the dimming range PWM has to be used. controlling both current and duty cycle allows for a little more flexibility in the end result and the color consistency at differet in tensities. (some day some people much smarter than I will figure out a controller and driver combo to do this all from the controller)

[Terminatermule]

Thanks for the reply. I had been looking at the 4101's as I wanted a driver similar to that offered by stevesleds but I wanted a little more control over what it could do. Basically a slight rejig of his driver boards to offer a few more adjustments.

I had not really looked at the LDD units, I will sus them out now.

What would you want for the boards you have? May be worth building one to compare just for fun anyway.

PS:

Just found a thread on thereefuge and realised that the boards they have the pics up of are yours, could I please hassle you for a copy of the eagle file for them to tinker with? Also what did you think of using the sockets as opposed to just soldering thru hole, do you think the cost was worth it?

Edit again:

Ok so I just read that whole thread, are you "magicJ" SurplusO2? If so (and I do suspect so, lol) can I get in on the purchase of the ldd's and boards? I am going to be driving ~100 LEDs including a few 350ma moon lights.
Cheers Glenn

[der_wille_zur_macht]

(some day some people much smarter than I will figure out a controller and driver combo to do this all from the controller)

Hey give yourself some credit. :lol: I did actually design a version of the CAT4101 board that had a digital pot (I2C controlled) on the Rsense pin, as well as the "standard" dimming control via PWM on the EN pin. Never "released" the design though as that was more or less right at the time that I was totally giving up on the CAT4101. Besides the fact that it's not cheaper than the LDD, it's also IME pretty darn fragile. I am 100% LM3409 at the moment. If I wanted something under 1A I would probably buy LDDs.

Regarding your overall approach - I get it, but I wouldn't do it purely to preserve the color for the white LEDs. To me, that doesn't add much value, especially since the whole reason why people are usually dimming whites is to "blend" and get a certain color. If the whites have some spectral shift at different nominal currents, all that means is your response curve (white LED current vs. overall system color) won't be totally linear, which is probably something that most people won't even notice, and at worst can be fixed with a small tweak of the knob.

Instead, I would want to control current separately from PWM dimming to preserve efficiency. If you have a driver running at 2A, but have dimmed it 50% via PWM, you'll be effectively running with the efficiency of a 2A drive current. By contrast, if you just redesigned the driver to run at 1A, you'd have slightly better efficiency.

In the end IMHO the best approach is to design the driver such that the drive current is pretty close to what you "normally" want, then use dimming for MINOR tweaks and "effects" like sunrise/sunset.

[O2Surplus]

Thanks for the reply. I had been looking at the 4101's as I wanted a driver similar to that offered by stevesleds but I wanted a little more control over what it could do. Basically a slight rejig of his driver boards to offer a few more adjustments.

I had not really looked at the LDD units, I will sus them out now.

What would you want for the boards you have? May be worth building one to compare just for fun anyway.

PS:

Just found a thread on thereefuge and realised that the boards they have the pics up of are yours, could I please hassle you for a copy of the eagle file for them to tinker with? Also what did you think of using the sockets as opposed to just soldering thru hole, do you think the cost was worth it?

Edit again:

Ok so I just read that whole thread, are you "magicJ" SurplusO2? If so (and I do suspect so, lol) can I get in on the purchase of the ldd's and boards? I am going to be driving ~100 LEDs including a few 350ma moon lights.
Cheers Glenn

LOL - I'm not "Magic J". Here's a link to the newest version of the 5up LDD-H PcB -Reef Central Online Community - View Single Post - Meanwell LDD driver: for those who want to dim to 0 using Arduino (http://reefcentral.com/forums/showpost.php?p=21241562&postcount=936)

[KRavEN]

Hey give yourself some credit. :lol: I did actually design a version of the CAT4101 board that had a digital pot (I2C controlled) on the Rsense pin, as well as the "standard" dimming control via PWM on the EN pin. Never "released" the design though as that was more or less right at the time that I was totally giving up on the CAT4101.

Any chance you still have the eagle files for that? I'm interested to see how you did the I2C digital pot.

[der_wille_zur_macht]

I will look but probably not. That development work was done on a laptop that I no longer have, and when I turn over PCs I tend to only keep the stuff that had been stored in a repo (which is pretty much just the projects I've published here or in other threads). I tend to end up with dozens of abandoned projects every time I have a burst of creativity, archiving them all would be quite the task.

If you spend some time looking at mouser or another electronics supplier you'll find plenty of digital pots though so you should be able to find something that works.

[zachts]

Regarding your overall approach - I get it, but I wouldn't do it purely to preserve the color for the white LEDs. To me, that doesn't add much value, especially since the whole reason why people are usually dimming whites is to "blend" and get a certain color. If the whites have some spectral shift at different nominal currents, all that means is your response curve (white LED current vs. overall system color) won't be totally linear, which is probably something that most people won't even notice, and at worst can be fixed with a small tweak of the knob.

Instead, I would want to control current separately from PWM dimming to preserve efficiency. If you have a driver running at 2A, but have dimmed it 50% via PWM, you'll be effectively running with the efficiency of a 2A drive current. By contrast, if you just redesigned the driver to run at 1A, you'd have slightly better efficiency.

In the end IMHO the best approach is to design the driver such that the drive current is pretty close to what you "normally" want, then use dimming for MINOR tweaks and "effects" like sunrise/sunset.

We're thinking along very similar lines, the efficiency gain is a big benifit, also I like the simplicity of having one driver that can be adjusted to suit the current needs, makes project implementation eaisier on a DIY level, a one part fit's all sort of appoach.

my main point with the "whites" was that I intend to use red, green, and blue in suplementing my white (probalby a remote phosphpor type rig when all is said and done) and i want their relative intensity and the total "white" color to dim as one rather than shift color as it would if only using pwm. (since if you have one color dimed slightly to achieve the all on color then it will have fewer dimming steps available to it and shift intensity more quickly than the other colors) Mainly I want to aviod what the Philips L prize bulb did and have a light that turns red at low dimming values due to the diferent response of each color LED. I tend to over complicate things sometimes, which is why I havent jumped into controller design yet, I'll end up building a monster that can controll my whole house from another country and spend two years developing it :lolspin:

[der_wille_zur_macht]

Ok, gotcha. If you can deal with each color on it's own driver and sending a separate signal to each color's driver you can fix the rest in software - essentially build a different response curve for each color with respect to "total" dimming. So if your overall dimming level is 50%, the controller knows that means the reds are 45%, blues are 52%, and whites are 50%, or whatever it works out to be. You'd basically be writing color correction software, which would be a pretty neat challenge. But probably a unique challenge, as most people want a significant change in spectrum during "total" dimming (usually more blue at lower light levels though).

[Terminatermule]

Thanks Guys.

I hate that, I had found this thread somewhere in the middle, read a bit, decided I wanted to read it through, so I posted the initial questions, then started reading it tip to toe, but in doing so I missed the late discussion of the the LDDs.

Ok O2, The other thread sort of read like you were possibly the same person, I'm sure I read in their a claim to having designed the boards, then the pic had your name on the silkscreening.

I will evaluate my layout today and I may have a few other questions for you guys. Thanks for the input, has been great.

Cheers Glenn

[zachts]

Ok, gotcha. If you can deal with each color on it's own driver and sending a separate signal to each color's driver you can fix the rest in software - essentially build a different response curve for each color with respect to "total" dimming. So if your overall dimming level is 50%, the controller knows that means the reds are 45%, blues are 52%, and whites are 50%, or whatever it works out to be. You'd basically be writing color correction software, which would be a pretty neat challenge. But probably a unique challenge, as most people want a significant change in spectrum during "total" dimming (usually more blue at lower light levels though).

that does sound like an intersting challenge, just one I'm not ready to tackle just yet :) for now I'm sticking good old anolauge simplicity for some of the work but at some point the software based approach would be the way to go. (future projects, yay!)

[MagicJ]

Edit again:

Ok so I just read that whole thread, are you "magicJ" SurplusO2? If so (and I do suspect so, lol) can I get in on the purchase of the ldd's and boards? I am going to be driving ~100 LEDs including a few 350ma moon lights.
Cheers Glenn

:lolspin: No he is not me, although I wish I had the ability to knock up some great PCB's like O2surplus can :D

[indutor_ki]

DEVS

Here's a dual CAT driver that will work. As it is, both channels are independent of each other. If you want to Parallel the channels, just connect the negative side of your LED string to both negative terminals on the board. I included pots with both chips for current adjustment. All you'd have to do is balance the load between the two CAT chips by adjusting each one to drive half your target current. For example- Say you want to drive a string of six XPG's to 1400 ma. Connect the string to one channel only, power-up, and adjust the current to 700ma. Now connect to the other channel only, power up, and adjust it for 700ma output. finally connect both channels and check the current, It should now be around your target of 1400ma.This design is nice because you're not forced to parallel drive if you don't need to, plus it has a 5V reg included for powering up the driver for situations where there is not a controller providing the 5V turn on signal or dimming signal. Feel free to mod it any way you like.

hello, first let me thank you for your work and for sharing it.
i want to now one thing about the dual cat4101 driver you design. i don't know much about electronic but in that board you are using a 12v regulator, but the led and the vin of the cat, i believe is 5v. why is not a 5v output for your regulator.
sorry if i missunerstand

[O2Surplus]

hello, first let me thank you for your work and for sharing it.
i want to now one thing about the dual cat4101 driver you design. i don't know much about electronic but in that board you are using a 12v regulator, but the led and the vin of the cat, i believe is 5v. why is not a 5v output for your regulator.
sorry if i missunerstand


I probably made a mistake when I drew up that PcB and used a 12V reg instead of the 5V version. Both regulators look the same. Just substitute a UA7805 in place of the UA7812, and it will work fine.

[indutor_ki]

Ok, thank you for your attencion.
I think i will try the smartcat, i will try to convert it to gerber and send it seeedstudio, to make some pcb's.

[marspeed]

if anyone needs any cat4101 i have 25 to many i also have some 3 up boards left over

[indutor_ki]

Ok, good to know. I'm still waiting for the pcb to arrive.

[ShadowNoob]

I was wondering what your opinions were on TPS92510DGQ from Texas instrument. I plan on running 12 cree xp-g r5 5w per driver they run at 3.25v 1500ma. Thats 39v total, That was the only chip i found that would fit the requirements of 1.5a with 39+v. Im not saying I plan on running it at that just looking at possibilities. I'm leaning more towards running them at 1000mah. But if i decide to just run them at 1500mah i would like to test one out.

[ShadowNoob]

i just seen the new LM3409 at mouser and its a 2A 75v max so thats another one and its a bit cheaper.

[ShadowNoob]

Guess this thread is dead

[JRx]

where from to buy theses lm3409 led driver boards, have smbdy for sale?
thanx

[asid61]

The SN3910 is a great led driver tan can be run directly off rectified AC. So you can run something like 30 leds on it no problem.

Also, I am making LM3429 led boards. Great boost boards, with a max vout of 40v at least, but can go up to 70v with care in the components.
They get 94% efficiency across a wide range of voltages.

[zachts]

I'm just going to point out something that's been covered more than a few times, but needs to be reiterated from time to time for the newbies and inexperienced hobbyists that reed these forum posts.

Exceeding 50 volts on a DIY LED build is extremely dangerous to the DIY'er. Voltage over 50 volts presents a serious risk of fatal electrocution should you touch a live wire or have an led shorted to the heatsink, which is very common and often the lights still work just fine despite the short.

[asid61]

I'm just going to point out something that's been covered more than a few times, but needs to be reiterated from time to time for the newbies and inexperienced hobbyists that reed these forum posts.

Exceeding 50 volts on a DIY LED build is extremely dangerous to the DIY'er. Voltage over 50 volts presents a serious risk of fatal electrocution should you touch a live wire or have an led shorted to the heatsink, which is very common and often the lights still work just fine despite the short.

I apologize. I assumed anybody reading this thread would have ample knowledge of how to handle large voltage, as they would need a reflow oven to use either of the chips I posted.
The LM3429 is a boost driver, so it only provides however many volts are needed. So there is little risk of electrocution.

[stryke297]

Is this thread dead? I don't think DWZM has been online for more than six months.
anyway, I'm working on making a driver using the 3066 but none of the documents or images from 2009 are available or viewable on my tablet. I took a schematic from the driver manual and have been modifying it accordingly but there are things mentioned in the initial couple pages that don't exist in ky schematic.

I'm not going to post. Any specs yet in case this is dead,but if someone who can assist could reply or pm me I have it available.

Lastly, I know. This was a discussion thread but it's painful scrolling through 108 pages just to stay relevant with a reply especially since only the first 15 or so pages were really crucial. Someone should have made a closed thread sticky with all the PSU Led and driver DIY information seperate from the discussions. Dwzm did a good job with links to other threads in his first post,but without a recapture when the bulk of the discovery is done it has a diminished effect.

That being said this website is absolutely one of the best places on the Internet for this type od DIY

[jmgelba]

Looks like I'm too late for this thread but I'll ask this question anyway. I have 5 LM3409's that are controlled by a single digital pot that seems to have an issue. I can select the individual drivers, and the more I turn on, the more voltage seems to be injected into the iAdj pin. Any ideas? I'm wondering if I need lower value resistors to create a stiffer potential divider and maintain the desired dimming voltage. Currently using 10K on the 5V end, and a 5K digital pot to GND giving a max of 1.667V Seeing as the iAdj pin is internally clamped I might bring that 10K down to 1K and provide a few mA instead of the 0.3mA it currently has. Thoughts?

[O2Surplus]

Looks like I'm too late for this thread but I'll ask this question anyway. I have 5 LM3409's that are controlled by a single digital pot that seems to have an issue. I can select the individual drivers, and the more I turn on, the more voltage seems to be injected into the iAdj pin. Any ideas? I'm wondering if I need lower value resistors to create a stiffer potential divider and maintain the desired dimming voltage. Currently using 10K on the 5V end, and a 5K digital pot to GND giving a max of 1.667V Seeing as the iAdj pin is internally clamped I might bring that 10K down to 1K and provide a few mA instead of the 0.3mA it currently has. Thoughts?


Can you post up a schematic of the digital pot circuit? I've built plenty of LM3409 based drivers using conventional 250k ohm potentiometers for analog dimming. Since digital pots should behave similarly to their analog cousins, may be a "higher value" digital pot will cure your problem?

[jmgelba]

Sure, I created a pictorial that matches the schematic for simplicity. Its a really simple idea but as I said, the more drivers that are running, the higher the voltage each dim pin sees.

http://i1181.photobucket.com/albums/x429/regal-electronics/MULTIDIM.png (http://s1181.photobucket.com/user/regal-electronics/media/MULTIDIM.png.html)

[jmgelba]

Changing the 10K to 1K does nothing. The added current still doesnt control the dim pins.

[O2Surplus]

Changing the 10K to 1K does nothing. The added current still doesnt control the dim pins.

Post a schematic please?

[jmgelba]

I did. Couple of posts up.

Its just a potential divider with the branch gong in to each dim pin.

[O2Surplus]

I did. Couple of posts up.

Its just a potential divider with the branch gong in to each dim pin.


I think your pictures or attachments are being blocked by the Mods until your post count is a little bit. I'd love to be able to help you, but without being able to see what you're doing, it's impossible right now.

[jmgelba]

Ahh got it. Wasnt aware that they were blocked.

TI support says the design should work and its being escalated up the food chain.

[feilibo]

Hi guys,


I am working on a project, using the LM3409 buck converter. I saw that you had some interesting discussions going on about that chip, and I wondered if you could have a look at my problem?

The constraints are:
Vin 12 - 40V, Vout: 9V, Iout: 1-5A, frequency: approx. 500kHz.
Shunt: 47m Ohms
Coff: 2nF, Roff: 220 - 10k Ohms.

I simulated the project, and everything was fine.
When I built it, I saw that there are several very short on- and off- switching states within one free-wheeling cycle. The time between them is approximately the off-time.

Now I red the datasheet, and that says, that the LM3405 switches the + and - comparator inputs with every cycle - leading to an offset of 24mV.
-> the current has to decrease by more than 0.5A before the next switching cycle - if a shunt of 47m Ohms is used.

This is a problem, because it leads to a very high inductor current ripple and to many switching cycles, which leads to a thermal problem of the switch.

If the current is reduced, or the off-time is reduced, the switching cycles within one free-wheeling period become less.

Does someone have an idea where this problem might come from and what could be done about it?
Did anyone have a similar problem?

Thanks,

Philipp

[twowordz]

Hi,

I'm using the CAt4101 board with an arduino.

My LED strings don't turn on. I think the issue might be the ground but I'm just not sure how to wire it to the arduino and the power supply.

I have a 24v 5A power supply with 100-240v input. It has V- V- V+ V+, do I connect the ground pin on the arduino to the V- on the power supply?

I fried an arduino by connecting the digital ground to V- (I wasn't paying attention)...

http://i.imgur.com/DGKy8RC.jpg

Thanks

[O2Surplus]

Hi,

I'm using the CAt4101 board with an arduino.

My LED strings don't turn on. I think the issue might be the ground but I'm just not sure how to wire it to the arduino and the power supply.

I have a 24v 5A power supply with 100-240v input. It has V- V- V+ V+, do I connect the ground pin on the arduino to the V- on the power supply?

I fried an arduino by connecting the digital ground to V- (I wasn't paying attention)...



Thanks

Yes- Make sure that your CAT4101 board & the Arduino's ground pin all connect back to the V- terminal of your power supply.

[twowordz]

Thanks for the quick reply!
Now I need to get another arduino. When I get it to work, I might switch to a Raspberry Pi.

[theatrus]

Also make sure you are not feeding the Arduino 24V as its power input, as it isn't designed for this.

[twowordz]

Yes sir. I had the arduino connected to my laptop when I connected the digital ground to the V-. The laptop shut down and now the usb port doesn't work...

Oh well, company laptop, I'll have the techs repair it.

[twowordz]

Another question...

Now that my arduino is toast, can I just take a 5V supply and connect the + to both the PWM and 5v input on the board to turn on the strings at 100%?

If yes, would the negative wire on the 5v supply go to the V- on my 24v power supply?

[O2Surplus]

Another question...

Now that my arduino is toast, can I just take a 5V supply and connect the + to both the PWM and 5v input on the board to turn on the strings at 100%?

If yes, would the negative wire on the 5v supply go to the V- on my 24v power supply?


Yes & yes.

[twowordz]

Alright, it works but I think the diodes I purchased are fake... no where near as bright as I was expecting.

[O2Surplus]

Alright, it works but I think the diodes I purchased are fake... no where near as bright as I was expecting.

Not bright eh? Have you verified how much current they're being driven at? Maybe it's less than you assume?

[twowordz]

The diodes were sold to me as XPE2. The spec says they should have a forward voltage of 3.15 @ 1000 mA. I have 7 in a string and the drop is 15.3v. The actual part they told me it was is XPEBWT-L1-0000-00BE7.

They came on a star pcb but the print doesn't look legit... What do you think?
http://i.imgur.com/Fegi5hw.jpg

http://i.imgur.com/3fGg5nd.jpg

I bought the CAT4101 back when I had a reef but moved across provinces and left all the hardware sitting in a box for 3 years. I recently decided to try it out just for fun. That's why the lights are white, I don't really have a use for the other colors right now.

[perkint]

As O2Srplus said, test the current. If they are being driven on a low current, you'd see a lower voltage across them and less light.

Cree only supply the actual emitter - the star is usually supplied by whoever reflows the emitter on to it, so the lettering could be done by anyone and still a genuine cree LED.

Tim

[twowordz]

Hi Tim,
How do I test the current?

I've set the power supply to 24v using the trim pot on it. The PWM on the CAT4101 is connected to 5v. If I recall correctly, the CAT4101 board as designed here, is 700mA so the voltage drop on the xpe2 should be 3.05.

Now 15.3 / 7 = 2.19 so I'm pretty far from what I should see right?

[proietti]

The diodes were sold to me as XPE2. The spec says they should have a forward voltage of 3.15 @ 1000 mA. I have 7 in a string and the drop is 15.3v. The actual part they told me it was is XPEBWT-L1-0000-00BE7.

They came on a star pcb but the print doesn't look legit... What do you think?


I am sorry to say I don't think they are XPE. All the XPE's I have ever purchased no matter what star/round board base the diode is green. Check out the Cree XPE data sheet.

[twowordz]

Here's the datasheet from cree (http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXPE2.pdf).

The picture shows a yellow diode.

http://i.imgur.com/IJytbxz.gif

[perkint]

Hi Tim,
How do I test the current?

I've set the power supply to 24v using the trim pot on it. The PWM on the CAT4101 is connected to 5v. If I recall correctly, the CAT4101 board as designed here, is 700mA so the voltage drop on the xpe2 should be 3.05.

Now 15.3 / 7 = 2.19 so I'm pretty far from what I should see right?
Using a multimeter on the ammeter setting. It needs to be part of the circuit (ie the +ve supply goes the the ammeter and then the ammeter connects to the +ve in on your LEDs).

Or, just drop a 9V battery across three of them and see if they look brighter then when normslly powered up. A 3V source across one is easier, if you have one...

2.19 is about riht for XPE at 700mA. For XPE2, it would be more like 10mA!!!!

Tim

[zachts]

Hi Tim,
How do I test the current?

I've set the power supply to 24v using the trim pot on it. The PWM on the CAT4101 is connected to 5v. If I recall correctly, the CAT4101 board as designed here, is 700mA so the voltage drop on the xpe2 should be 3.05.

Now 15.3 / 7 = 2.19 so I'm pretty far from what I should see right?

Another simple method to use if your meter can't handle amps (some only measure mA) you would need a meter with a 10amp setting(usually a separate plug for the positive lead.

you can use a resistor wired in series with the string. a 1ohm resistor works fine for this you will want at least a 1 or two watt resistor so it doesn't burn up during the test. you then set the meter to measure milivolts or volts and measure across the two ends of the resistor. using a 1ohm resistor the voltage reading equals the current. I.E. 700mA current would give a voltage of either 0.7volts or 700mV depending on the setting on your meter.