I want to switch the power on/off to the WIFI module using an IO pin of a microcontroller, peak current is 200mA, average current 100mA. Which MOSFET(part number) should I use?


simulate this circuit – Schematic created using CircuitLab


closed as unclear what you're asking by Matt Young, Gustavo Litovsky, Nick Alexeev, Dave Tweed, Anindo Ghosh Sep 28 '13 at 21:30

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  • \$\begingroup\$ Bob. Oh. A PMOSFET. \$\endgroup\$ – Ignacio Vazquez-Abrams Sep 28 '13 at 8:49
  • \$\begingroup\$ You might look at the parts specifically marketed for switching USB VBus \$\endgroup\$ – Chris Stratton Sep 28 '13 at 19:48

As I understand it your circuit is wrong - it's showing an N channel mosfet wired as a source follower and this means you're likely to get about 2 or 3 volts out of it when "switched on".

You need a p channel mosfet with source tied to incoming power and drain connected to the output. Pulling the gate low will activate the FET, returning the gate to 5V will deactivate the fet but make sure you get one with \$V_{GS(threshold)}\$ quite low - maybe about -1V typical and -2V max.

The device Wouter has linked (IRF7205) might work OK but it's threshold range might mean sometimes it doesn't work (if you built a hundred maybe 5 wouldn't work as expected).


In such a situation I use an IRF7205. There must be lots of alternatives.


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