Hello! I am trying to make a buck converter using an arduino. I need to use a P channel mosfet as a high side switch. I have made a circuit like this [Screenshot_2] When I use the external power supply, whose ground is connected to arduino ground, the mosfet just stays on. If I use the 5v from a…

One approach (although R4 should connect to the I/O pin, not the base). Google "arduino pmos high side switch" for others. [image]

Thats what it always showed on internet about p channel mosfet high side switching, so I connected it like that. But its interesting that one buck converter tutorial showed the mosfet other way around, and it just seemed like an error to me. Should I try to use it the other way around, source to th…

[image] okeypro: Should I try to use it the other way around, Yes. Simple check: with confused S/D the MOSFET is always ON! See the diode in the complete symbol. A buck converter is a tricky circuit that should not be used for ordinary applications.

Oh nevermind! The mosfet was right orientation. I somehow mixed up the emmiter and collector of the npn transistor! It seems to be working now! Such a stupid mistake. I have one question, for example I want to use 92V with the mosfet. That means I cant connect ground to the mosfet, as the voltage wo…

[image] okeypro: What do I do in this situation? Both transistors must withstand that voltage. Such transistors exist, you only have to find them :slight_smile:

I would have thought that R2 (what I would call a drain resistor) would be between the gate and Ground or at least the low side of the MOSFET. With R2 in your circuit and the high impedance of the transistor and MOSFET, causing very low current through R2 will have the gate at 12 V or close. I cou…

The 100Ω base resistor is overloading the output pin, increase it to 1000Ω.

[image] wwbrown: R2 (what I would call a drain resistor) would be between the gate and Ground This Gate discharge resistor always sits between Gate and Source. Source is the positive supply with a P-channel MOSFET so here it's a pull-up resistor. [image] JCA34F: 100Ω base resistor is ove…

Using P channel mosfet with arduino

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DrDiettrich June 6, 2022, 7:38pm 4

Your circuit diagram is correct except for M1.
You only have to connect everything just as in your updated circuit diagram. Double check or fully rebuild your circuit. Did you confuse C/E pins of Q1 or S/D of M1?

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Using P channel mosfet with arduino

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