PWM control of 25amp motor

[shobley]

I have a project that requires the PWM control of a 25amp fan (in a car dash) - is there any problem with wiring the gate of a suitable mosfet (or pair) through a an optoisolator to an arduino pin?

I've done this successfully in the past, but only with about 10amp loads.

Steve

[Franklin97355]

I would say you would be OK as long as the frequency response of the opto can handle your PWM frequency and the mosfet is sized correctly.

[zener]

You will need a pretty beefy mosfet. Something 3 or 4 mOhm might work, and you will need a heatsink.

[Entropy]

Might want to look at Charles Guan's blog (etotheipiplusone.net) for ideas. He and Shane Colton (scolton.blogspot.com) do a lot of work involving controlling BIG motors.

[shobley]

Thanks - I will check that out.

[zener]

Historically this was done with two or more fets in parallel. But you might get away with a single one with very low RDSon. Just a follow up to my previous post.