DIY LED driver for reef lighting

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.
 
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.
 
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.
 
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!!
 
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.
 
kcress said:
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.
Click to expand...

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.
 
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
 
shirley386 said:
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
Click to expand...

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
 
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
 
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
 
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.
 
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...
 
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!
 
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".

shirley386 said:
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!
Click to expand...
 
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