Switching p-channel mosfet

Thread Starter

ivars211

Joined May 5, 2013
20
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:
 

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crutschow

Joined Mar 14, 2008
23,544
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.
 

Thread Starter

ivars211

Joined May 5, 2013
20
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:

crutschow

Joined Mar 14, 2008
23,544
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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