[dorkbotpdx-blabber] another LED array question

[Paul Stoffregen]

> That's an awesome chip!  I'd ask you where you found such a great IC but you
> might not want to divulge too many of your sources. :)
>   

Eric definitely deserves the "most awesome chip found" award for the 
TLC5947!!!

It even controls the current so you only need 1 resistor for every 24 
LEDs.  Pretty amazing.  12 bit PWM and all done on-chip which is a lot 
less coding that what I suggested!  It only costs $0.45 more per 8 bits 
than the simple shift register.

But it also only comes in a tiny SMT chip with a big thermal pad on the 
bottom.  Since it's acting as all those current limiting resistors too, 
I'm pretty sure you'll need to get those thermal pad well soldered to a 
bunch of vias and a big ground plane or small heatsink on the back side 
of the board.  Then again, figure 11 on page 11 of the datasheets seems 
to say the chip can dissipate quite a lot even in free air, which I find 
pretty hard to believe.  But there is a thermal shutdown circuit that 
kicks in at 162 degrees C.....  maybe a good idea to use lead-free 
solder!  (normal SnPb melts around 180C)

> Have you seen a similar part to the one
> you mentioned but in a 16-bit register?
>   

Nope, though that doesn't mean it's not out there.

But the 8 bit part comes in DIP package which is pretty nice if you're 
going to "experiment" without having to etch/buy a PCB.