The TLC5947DAP (datasheet) is a powerful LED controller chip from Texas Instruments. It has 24 channels of individually-settable 12-bit PWM, each switching a current-controlled sink driver. The maximum current is set by a single external resistor for the whole chip. This makes the chip perfect for driving 24 LEDs with precise brightness control; ideal for controlling 8 RGB LEDs. The current sinks eliminate the need for external resistors for each LED, with correct supply voltage and heatsinking.
Controlling the chip is easy. Much easier than the TLC5940 (16 channel) version, actually. The TLC5947 has an internal PWM clock, so you only have to shift data into the TLC5947 and pulse the latch line. The interface can be configured exactly like a ShiftBrite connector. Each of the 24 channels accepts 12 bits of data, so you simply shift out 288 bits, pulse the latch signal, and each channel is displaying the new brightness setting.
This version of the TLC5947 is packaged in TI's HTSSOP thermal case. The silicon is located on top of a metal substrate that is exposed on the underside of the chip. TI provides specifications for correct PCB layout, and I have created an Eagle part (download) based on these specs. For the best thermal performance, you should add 13 mil ground vias as shown in this image:
We currently have a surplus of these chips, purchased for a series of upcoming new products. Due to worldwide semiconductor shortages, this particular chip has been nearly impossible to buy for more than half a year. We finally saw a roll of 2,000 appear on Arrow's website, and it could only be sold as a complete reel. Since there was really no other way to get the quantity we needed, we decided to buy the whole reel and then make half of it available as a service to the general (electronics hobbyist) public.
As of the time of writing, we are the only supplier who can sell you this chip in small quantities and ship immediately. All other suppliers have very limited quantities and 18 to 22 week leadtimes.
Since we have to cut the tape and re-seal for each purchase, we're setting a minimum of 5 on this product.
