zcwaa22:
As for the power dissipation the TLC5940 datasheet say's it has a power dissipation of 2.5W- fungus you stated 1.5W is this just incoraporating a safety margin?
That's at 25°C, but ... if you run it at 2.5W without active cooling it won't stay at 25 degrees for very long!
Where will the temperature level out? That's hard to say, but the datasheet says to remove 19.65mW per °C.
1.5W seems like a safe value and it's one you can achieve easily with just an extra external resistor per LED. That's why I picked it.
It might be able to handle more than 1.5W but I doubt it's anywhere near 2.5W without heatsinks+fans, etc.