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Low Vgth P-Channel MOSFET driving with Arduino

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elefurtronik:
Hello,
I am trying to drive max -1v Vgth p-Channel mosfet with arduino by usin bc337 npn transistor. However, my MOSFET never turns off. I think this was caused high voltage which goes to the gate even though my bjt was turned off.
How can I turn off my mosfets? How can I apply a voltage to the MOSFET gate 0V for to close and over 1V to open.
Plase help me about it. I tried voltage divider but it didn't work. I also tried Zener diode.

wasedadoc:
Remove Q1 and replace I1 with a 1K resistor.  If the simulation still shows M1 passing significant current, then the simulation is wrong.

CountChocula:
Try replacing M1 with a different P-MOS… my guess is that there is something wrong with the model you're using, so maybe trying a different one will help you ferret it out.

elefurtronik:

--- Quote from: wasedadoc on February 02, 2023, 01:45:43 pm ---Remove Q1 and replace I1 with a 1K resistor.  If the simulation still shows M1 passing significant current, then the simulation is wrong.

--- End quote ---
Hello,
I have just made this simulation to show my real circuit. It doesn't work in reality, I even tried in reality to use 1k resistor instead of 25k. However, my mosfets don't turn off.


--- Quote from: CountChocula on February 02, 2023, 01:49:49 pm ---Try replacing M1 with a different P-MOS… my guess is that there is something wrong with the model you're using, so maybe trying a different one will help you ferret it out.

--- End quote ---
I also tried to use an N-Channel mosfet instead a BJT. However, it doesn't work either. I am just talking about reality not for simulation. My diagram doesn't work in reality.

Peabody:
P-channel is the right mosfet, not N-channel.  When your NPN is turned off (Arduino output is low), then the pullup resistor on the mosfet gate raises the gate voltage to 6V, which turns off the mosfet.  So your circuit should work.

What is the gate voltage when the NPN is off?  If it is 6V, and the source voltage is also 6V, then the mosfet must be off.  Are you sure you haven't reversed the drain and source?  If they are reversed, then current would flow through the body diode even if the mosfet is off.  The source should be connected to the 6V rail, and the drain connected to your load.

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