Looking for an IC

Hey Guys,

Does anyone know of an IC that has multiple channels that can drive a low power transistor gate like a 2N222 from a serial input?

Ive seen the constant current sink PWM drivers like the 5940 but i need something that can drive.

I need to be able to pwm 30 transistors from 1 arduino 2009.

Would a serial to parallel latching shift-register IC work for you? Clock the data in, latch it over to the transistor outputs - do that over and over again for PWM (not sure about speed, tho). You would also need a 2-4 of them daisy chained to get to 30 output pins, depending on the size of the register (8 or 16 bit):

http://www.arduino.cc/en/Tutorial/ShiftOut

most hc series chips will have little trouble with the speeds the arduino can do

but shift registers seem to be exactly what your looking for

If you put pull-ups on the outputs of the TLC5940 (the pinout of the DIP version makes it easy to do this with a couple of SIP resistor networks), you could use it to drive 16 2N2222s. Just invert the duty cycle numbers, because the 5940 would be turning the transistors off when its outputs were on.

Depending on the nature of the load, you might even be able to omit the transistors.

Hey guys I really appreciate the input.

Would using shift registers take a lot of overhead to keep them going? I would be using a PWM frequency similar to the arduinos I think 500Hz.

I had thought there could be a way to use the TLC5940 but couldn't wrap my head around it.

put pull-ups on the outputs of the TLC5940

So I would put a resistor from my supply voltage to the transistor gate and also the output of the TLC5940 to the transistor gate? So when the 5940's output is on, the gate is pulled low, and when the output is off the gate is pulled high? I wish i knew how to post a schematic....

Again thanks for the help.