Choosing the Best Arduino-Driven Switching Component

Thread Starter


Joined Apr 15, 2017
I have a very simple circuit which is just a battery and a motor. I need to switch on the motor using a bush button attached to an arduino.

The motor is 12v DC and has a stall current of 20A, which seems to be the limiting factor here.

I am currently planning to use an IRFZ44NS MOSFET to do the switching, but the more I research it the more I realize the Arduino isn't going to saturate the gate enough and heat is going to become a big issue.

Does anyone have any better suggestions? My only real requirement is it has to be relatively small to fit inside my project. As small as a MOSFET, lol.


Joined Mar 10, 2018
You could back into this by saying Pdisswitch < 1W.

So Pdisswitch = I^2 x Rdson or Rdson <= 1/400 <= 2.5 mohms

Go look for a MOSFET that meets that, or parallel some MOSFETS.

Logic level MOSFET of course.

Debounce the switch going into Arduino so you do not have an oscillating
signal for MOSFET gate drive. Also you might want to parallel 2 or more
pins on Arduino to help minimize Pdiss in the MOSFET from its turn on.
transient. Eg. give it more drive to allow it to turn on faster.

Also clamp the turn off transient from motor L with a diode for reverse
voltage protection.

Lastly note the R from MOSFET Gate to ground, Thats to keep MOSFET
off during processor startup when most modern UPs tristate their outputs.
Also there to absorb leakage so MOSFET does not turn on from leakage.
The Arduino powers up with all pins as inputs, so essentially floating.

Regards, Dana.
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