I thought the TLC5940 could drive (sink) up to 120mA per channel with VCC of 5V.
Ok i discussed this with a friend and the result was that i didn't understand what i was measuring more or less.but now that i understand what i'm measuring i am still not sure what to insert in the power dissipation equation for voltage. i think i will need more testing nonetheless.
hellosorry that this reply took so long, was swamped with work and needed some time to familiarize with the chip.i did some testing. first with a 22k Ohm resistor (had no closer value to 2k) theoretically letting 17,7 mA through and second with a 470 Ohm resistor one letting potentially 83 mA trough.then measured Volts and Amperefor a 10 cm strip (3 leds) i get between led strip anode an red cathode:1) 11,68V (directly attached to the anode and the cathode) 18,9mA2) 12,05V (same measuring as above) 18,24 mA
so am i right that only ((12,30 - 12,05) = 0,25V goes into the tlc chip which by my calculations would mean i am on the safe side for power dissipation?my calculation is based on: 20 mA (into the chip) 0,25 V(into the chip) and 12 outputs used (4 led strips per chip)
Most of strips are voltage based, not current based, I mean, they have resistor built-in to limit the current. TLC5940 is a constant current IC so I am not sure you really need it,