Re: [EE]: MOSFET as a digital switch by Tal .

Any P channel will do. Drive it with an open collector and a pullup resistor and you will have a good Vgs drive voltage of 12V (your high side voltage). Make sure your mosfet can handle 12V Vgs (otherwise, add another resistor for voltage divider). Also, I am not sure what are the charactersistis of the fan you plan to use. If this is an inductive load, you may need add a reverse diode parallel to it. Anybody wants to comment on this ? BTW, N chan can also do high side but the drive is a little bit more complex (e.g. a charge pump to generate voltge above your VDD) so typically you want to avoid it. Tal > {Original Message removed}