zcwaa22:
Ah ok! Thanks for clarifying that fungus!I'll definately be putting a resistor on each LED.
http://led.linear1.org/led.wiz says that a 15ohm resistor on each LED will dissipate 216mW per resistor which I guess leaves the TLC hardly anything to dissipate- does that soudn right to you?
At 120mA a 15 Ohm resistor will swallow 1.8V.
So...if the LED takes 2.4V, the resistor takes 1.8V, that leaves 0.8V for the TLC5940.
0.8V120mA16=1.536W total dissipation - that's within spec.
1.5W is still quite a lot of heat for a chip to dissipate though. It's going to get quite warm if you set all LEDs to full power for more than a few seconds (nb. I don't know how many LEDs will ever be on simultaneously...)
If it was me I'd use 16 or 18 Ohm resistors just because it's no effort and it reduces the load on the chip a little bit more.