CPU fan control with PIC

[SuzieW]

Hi,
I'm new here!
I want to use a PIC to simply turn on or off a 12Vdc CPU fan (no PWM). Should I use a MOSFET or a transistor. I also have another 12Vdc motor drawing from the same power supply. That motor is being controlled with a IRF3708 MOSFET. Will that be a problem?
Thanks!

 

[eblc1388]

I don't know why your post is not being answered earlier.

There is no big advantage of using one over the other. You can use either a transistor or a MOSFET to control a 12V CPU fan via a PIC output port pin. You will need a base resistor for the NPN transistor or a gate to GND resistor for the MOSFET.

Usually I would also add a diode across the fan to take care of the back emf when the NPN/MOSFET opens.

 

[SuzieW]

Could I use the IRF3708 mosfet (Vdss = 30V, Id = 62A) that I am using for my motor (I have some extra ones)? I seems so overrated though. Do you know of another mosfet that would be more suitable? Thanks!

 

[justDIY]

what are the specs on this "other" motor... is this some sort of peltier or water cooling setup?

the 37xx series are intended for switch-mode power supplies, that is why their current rating is so high, but you can certainly use them to switch smaller loads!

use whatever nfet you have handy, the 3708 is ok, since it offers a good RdsON at logic-level (+5v) control voltages. The IRFU3711 is physically smaller, and is rated at over 100amps at 20v

just visit the parametric search at International Rectifier and punch in your requirements, it will recommend a fitting switch for you.

 

[Thunderchild]

I can't see the point ? just hook the fans up to the power supply and what is the pic for ?