While waiting for my high brightness LED boards to come, I finally finished up the TLC5947-based board, which I ordered from Sparkfun’s BatchPCB service. I had made the LED holes too small so I had to surface mount solder each LED individually, which took forever.
It uses one TLC5947 per 24 channels, which does 12-bit PWM on each individual channel. All the MCU has to do is shift in 12 bits per channel, and send a latch signal. The PWM clock signal is generated by the TLC5947′s, which makes it a lot easier to use than the TLC5940′s. They can also be chained together. Here’s a video of it in action:
At full brightness it’ll draw about 2A of current. The TLC5947′s get pretty toasty when running them at 5V, but they work just fine at 4V and dissipate much less power.
I need to think of something cooler to display than just a cycling rainbow…
fantastic.
Can I buying it?
Hi, I do appreciate the interest.
I need to make another hardware revision to the board, so it’ll be a few weeks before I can sell any. The LED’s cost about $20 and the driver chips cost $3 each. I’d probably sell assembled ones for $50 to account for labor costs. I can sell it as a kit for $35. Still interested?
Yes. I would like to get some in kit form. Can you show the boards and maybe the code?
Too many cmoplmintes too little space, thanks!
I was wondering if you can help me with something. Do you think the TLC5947 can pwm AND still current limit high power leds if I put a transistor between the outputs and the led? So that a transistor with a amplification factor of 100 would give an 100*30=3000mAh current limit?
thanks in advance.
Lars, I think I saw a post on the TI E2E forum about putting transistors at the output of the TLC5947. I believe it can be done since all the TLC5947 does is sink current or open circuit. However relying on an external discrete transistor to do current limiting based on its beta is a very bad idea due to large beta variance in manufacturing and also over temperature and operating conditions.