Switching p-channel mosfet

Discussion in 'The Projects Forum' started by ivars211, Feb 18, 2014.

  1. ivars211

    Thread Starter New Member

    May 5, 2013
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    Hello, I have a question about p-channel mosfet switching. Assuming I have varying power supply (12-26v) in my circuit, but mosfet's gate-to-source voltage (IRFR9024N) is only +/-20v.

    I can use voltage divider to take the voltage down, but will it work in whole voltage range (12-26v)?

    Added the circuit below:
    [​IMG]
     
  2. crutschow

    Expert

    Mar 14, 2008
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    You can add a 10k resistor in series with the MOSFET gate and add a 10-15V zener between the gate and source (anode to gate). That will prevent any gate-source overvoltage, while still giving the full 10V gate-source voltage with a 12V supply.

    Note: You have the P-MOSFET drawn upside down. The load goes to the drain and the source goes to Vcc.

    Note: Convention is to draw the power (Vcc) towards the top of the drawing and the common (ground) near the bottom. It makes the schematic easier to read.
     
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  3. #12

    Expert

    Nov 30, 2010
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    Here. I cleaned up your drawing.
    ps, I left the mistakes in.
     
  4. ivars211

    Thread Starter New Member

    May 5, 2013
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    Thank you! Yes I know that drawing is upside down, sorry for that.
    I will try zener diode.

    #12, if you don't mind me asking, what's the software you used for schematic?
     
    Last edited: Feb 18, 2014
  5. #12

    Expert

    Nov 30, 2010
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    MS Paint
    ...
     
  6. ivars211

    Thread Starter New Member

    May 5, 2013
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    Ok, thanks.
    Just to make sure if I understood it correctly, would this arrangement work in ranges 12-26V?

    [​IMG]
     
  7. #12

    Expert

    Nov 30, 2010
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    It looks right to me.
     
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  8. crutschow

    Expert

    Mar 14, 2008
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    Here's a simulation of the circuit. I didn't have the models for some of the devices so I picked those that are sufficiently close. Note that it operates from a few volts (the low voltage operation depends upon the Vth of the MOSFET and the resistance of the load) up to 26V. Notice how the zener clamps the gate-source voltage to about 12V maximum.

    P-Mosfet Driver.gif
     
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  9. ivars211

    Thread Starter New Member

    May 5, 2013
    20
    0
    Thank you so much!
     
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