P-channel MOSFET sanity check

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1

I'm a newbie (so go easy on me) designing a Pro Mini shield for housing and controlling several modules (GPS, etc.). Modules are 3.3v and <50mA and powered from the Arduino VCC. I'm using a logic level P-channel MOSFET to switch the modules on/off high side via Arduino pins. The NX2301P seems a suitable option, I think.

A schematic of my circuit is attached. Questions:

  • Do I have this generally correct?

  • Are the resistor values suitable? All I know is that the pull-up resistor should be a high value to provide low current loss while ensuring the MOSFET is off (module powered off) when the Arduino starts.

  • I've read conflicting recommendations on whether the 150ohm resistor is necessary. Is it? Size/weight is critical, so I want to lose every component that isn't vital.

  • Any better recommendations for the MOSFET? It must be SMD.
    UPDATE: Is the DMP2305U a bit better choice? It has lower resistance at 3.3v and lower gate voltage, though I don't admit to understanding most of those numbers.

Thanks!

P-channelMOSFET.png
P-channelMOSFET.png701×443 33.2 KB

Need help with switch circuit - all 3.3v - mofset(s)?
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2

Yes it looks fine. The resistor of 150R is OK, I would include it if you are going to use PWM on the output if not the you could leave it out.
Yes that second FET has the lower turn on resistance but do you need it that low? Is their a cost diferance? Either would do.

3

Grumpy_Mike:
Yes that second FET has the lower turn on resistance but do you need it that low? Is their a cost diferance? Either would do.

There's a $.02 price difference and the 2nd one is a bit smaller with slightly better numbers, so I'll go with it.

Thank you for the reply!