SparkFun LED Driver Breakout - TLC5940 (16 Channel) BOB-1061

Greetings! I’ve been looking at the subject breakout, but I’m not sure what I would like to do would work. I’ve searched the forum and haven’t seen an answer (that I understand, anyway (o:) I already own Picobuck LED driver boards and Triple Output High Power RGB LEDs COM-15200, but I would like to set up an array of Picobucks driving the high power LEDs. I’m hoping I could use the LED driver breakout board as most microcontrollers don’t have enough PWM capability to do what I want to do directly. The tlc5940 data sheet calls these things constant current devices, so I’m thinking I can’t.

My question is: can I drive Picobucks with the TLC5940 breakout? I.e., can they PWM on all 16 channels, or are they only constant current? If not, is there such a device that is I2C or SPI that has many PWMs out?

Thanks so much for your time!

Hi DMax.

I haven’t tried it but yes, you should be able to drive a Picobuck from the TLC5940. They are constant current, but we add a pullup resistor on the output to take care of things if you’re not connecting a low impedance load like a LED.

Belated thanks; lots of things have happened; trying to get back to this project. Follow-on questions (o: Can I run the Arduino library for the TLC5940 on a ESP32 like a WROOM32 Dev Board? And while I’m at it, can I also run the Arduino library for the Qwiik Twist rotary encoder on the afore-mentioned ESP32?

Thanks so much for your time! (o:

Both libraries were written for the Arduino Uno and have not been tested on a ESP32, you’d need to give them each a try and see what happens. It’s possible that one or both might need some modification to work on an ESP32.

Ok, got a Sparkfun BlackBoard, and connected it up to the TLC5940 which are connected to Picobucks, and things all work, but I’m suspecting because of the TLC5940/Picobuck pull-up configuration(?) that the logic is reversed… (i.e., 4095 turns off LED and 0 is full on).

So, I plan on having about 100 high power 9 watt RGB LEDs you sell (I already bought 60 of them) hooked up to this system with 3 TLC5940s in series. When energized… BANG! all LEDs are on with a blinding white light (o: until the Arduino boots and writes 4095s to all the TLC5940’s registers. Is there any way I can switch that so upon power up LEDs are off until I ask them to come on?

Thanks for your time!

Try a 10K pull down resistor on all your CTRL pins and see if that keeps them off until needed.