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P-Channel MOSFET always on

AAnkur

New Member
Hello

I am using a MOSFET driver circuit with SI2303 as p-channel mosfet and SI2302 as n-channel mosfet.

I have given control signal (of 5V) on the gate of n-channel mosfet to turn-on and off the p-channel mosfet.



However, the p-channel mosfet is not getting off and I am constantly finding voltage on Output (marked as Point-A).

Please let me know what is the problem in this circuit.

Thanks
 

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rjenkinsgb

Well-Known Member
Most Helpful Member
Double check the connections? Those devices have internal diodes between source and drain, that will conduct if the two terminals are reversed.
 

danadak

Active Member
If you are measuring with a DMM, no output load, you will read a voltage
because of this -

1652696377266.png



There is still some drain current. And this does not account for leakage in the NMOS MOSFET Idoff
current at its Vgs = 0. Which can cause a non zero Vgs in the PMOSFET.


Regards, Dana.
 

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