Hi!
I want to drive up to ten high power RGB LEDs, using as little Arduino pins as possible.
Is there some kind of dream chip that does around 30 individually controllable PWM outputs, with an I2C interface? I gues I could use some transistors on the PWM outputs since each LED channel draws up to 350mA.
So, any good PWM I2C Mux chips out there?
Philips/NXP makes some I2C PWM drivers, they're intended for lower currents but as you say, you could use transistors. They are mostly 8 and 16 channel chips, but wasting two PWM channels shouldn't be a huge problem.
Yea, 30 outputs 350mA would mean a 10 amp chip. That would require a pretty big heat sink. Its not I2C but you could use the M5451 (up to 20mA per line) constant current driver with PNP transistors to multiply the output up to 350 mA. Of course if you did exactly that with no resistor, then you'd be relying on each transistor to have a similar beta (current amplification factor)... it used to be that transistors betas varied quite a bit. So doing it that way is sort of frowned upon especially if you are designing some kind of mass-produced device... Or you could have the transistor turn on hard and use a resistor to limit the current.