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In order to drive a voltage higher than the M1 Vgs, I think that limiting the Vgs voltage with a zener diode could be a good idea. It will be only switched once per minute. By this I mean that high frequencies are not needed.

M1 - main MOSFET. D1 - used to protect Vgs overvoltage. R1 - used to charge GS (to switch off M1 if M2 is open). R2 - used to limit the current through the zener.

M2 - used to drive M2 gate. R4 - used to pull-down switch off M2 during 3V3 signal is open drain.

Could be the following circuit a good aproach?

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ What supply voltage range is it to accommodate? \$\endgroup\$
    – Andy aka
    Commented Feb 3, 2022 at 8:45

1 Answer 1

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The zener diode is a pretty much standard solution for this, it should work fine.

Only major issue I can see in your schematic is M2, it requires too high gate voltage to be used with 3V3 control (threshold voltage of <4 V). But with another model transistor, no problem.

I'd use a slightly lower voltage zener diode, 12V or so, to have some extra margin if maximum Vgs of M1 is 20V. You could also use a slightly higher value of R2, to get a bit lower current and thus use a smaller (lower power rating) resistor for that.

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  • \$\begingroup\$ Related to M2 you are right. I chose "one MOSFET" and I forgot to delete the reference. It was my fault. \$\endgroup\$
    – robocotec
    Commented Feb 3, 2022 at 8:51

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