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I am switching a circuit with a resistive and inductive load that is supplied with 12V using a p-channel mosfet. I already have the option to switch the p-channel mosfet with a mechanical switch (SW3) and have added a solder-jumper to an esp32wroom I/O in the design (JP3).

The p-channel mosfet gate is pulled high in the default state (Q19 does not conduct) and can ideally be pulled low with the switch aswell as the esp32wroom I/0 27. Since this is already on a pcb, i can only change the resistance of R23 and/or add another small component bridging the solder-jumper JP3.

Can I safely connect the 12V gate to the esp and use it to pull it low if i adjust the resistance/add another resistor at JP3? If so, what do I need to do ?

Clarifications to understand the image:

  • Load is between +BATT and GND
  • label power_switch is connected to esp32wroom I/0 27
  • JP3 is an smd jumper pad that would fit a 0805 component

enter image description here

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No because the pullup will subject the ESP32 output to 12V. This will cause the upper ESD protection diodes to conduct the 12V to the VCC rail and probably completely destroy the device.

The standard method is to use a bipolar or n channel mosfet to drive the gate.

schematic

simulate this circuit – Schematic created using CircuitLab

M2 needs to be a logic level gate NFET and M1 needs to support a Vgs of 12V (which shouldn't be an issue).

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