MOSFET drive for PWM control

You have the mosfet source and drain reversed. And make sure the mosfet has a gate threshold such that it is always fully turned on with the available gate voltage.

You might want to put a resistor in series with the mosfet gate, to protect the micro against any spikes transmitted back through the mosfet gate capacitance, or in case of mosfet failure.

You don't say what speed you want to switch the mosfet at - if it is fairly fast (>10kHz say) you may need to review the gate drive current vs gate switching charge.

I assume there are supply decoupling capacitors you havn't shown? You need at least one between the regulator "GND" and "In" and one between the micro Vcc and Vss. Maybe many more depending on the micro.

I would also put transient suppressors and maybe some series impedance on the input and outputs - the details depend on the environment and what you are switching.

Oops! Thanks. Hopefully I would've spotted that when doing the full circuits.

I guess that's good design. MOSFET failure or Micro failure = board failure. Replace board.

I'll have a look at that now. It's a PWM (constant frequency) which would have a min pulse width of about

Yes, there are a few. Circuit was drawn to keep it simple.

OK. It's switching a resistive load, but there will be some inductance in the leads I guess (about 6' / 2m).

Thanks again for the comments.