Quote Originally Posted by Byte_Butcher View Post
I use a 16F684 and N-channel MOSFET to PWM control power to a 50 watt 12 volt heater element @ 100Hz with no issues.
I suppose the question is how much current is Megahertz talking about? Small 25-50W halogens, or 250 watt driving lights?

As long as the frequency isn't too high there shouldn't be any trouble driving an N-channel MOSFET directly from a PIC. For driving a halogen lamp there's probably no need for more than about 100 Hz.

If your PIC is running at 3 volts or less, then the choice of logic level high current FETs does diminish greatly and a driver circuit may be necessary.

Steve
Hi Steve, this is the only mosfet I could find locally, I am in India currently and I have to develop this using easily available components. Though I will try once again to find P-Channel, but I would like to request you if you can upload the circuit here for N-Channel mosfet you use for 12V - 50W heater.

I need it for 50W @ 12V halogen.
My PIC is running on 5V.
Widely available mosfet is IRF540 (N-Channel)

All help is much appreciated. Thanks