I have the following MOSFET driver circuits for high side P-Channel MOSFETS. The circuit works for supply voltages up to 20 volts. It gives some satisfactory results for it's range, but I would like for it to work up to 80 volts. Assuming I have selected a P-Channel MOSFET that can withstand the voltage, what considerations should be made to the driver? What ratings should I select for the transistors?

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I want the circuit to only draw current when the gate is actually being charged and discharged. My current setup draws current when the gate is held low (on) indefinitely, which I would like to address, but am not quite sure how. The input for AH is 5v btw.

  • \$\begingroup\$ I assume this is a high-side since there is no reason to use a PMOS over an NMOS in a low-side driver. For a high-side driver, at 80V, you should just use a high-side NMOS and make a high side gate driver for that. IMO, the effort you will go to to prevent the max Vgs from being exceeded when you pull the gate LO to to turn off the PMOS will be about the same as that required for a high-side NMOS driver, and the NMOS will be cheaper, more efficient, and more available. \$\endgroup\$ – DKNguyen Dec 10 '19 at 4:13
  • \$\begingroup\$ @DKNguyen I must use a P-Channel MOSFET on the high side in my project for various reasons. \$\endgroup\$ – Judson Hudson Dec 10 '19 at 4:18
  • \$\begingroup\$ What are those reasons? I am unaware of any situtation where you MUST use a PMOS. \$\endgroup\$ – DKNguyen Dec 10 '19 at 4:19
  • \$\begingroup\$ The P-MOS can be drain-tied to my N-MOS, allowing for for placement directly under it on the circuit board, reducing board space. \$\endgroup\$ – Judson Hudson Dec 10 '19 at 4:23
  • \$\begingroup\$ You will be wasting a lot of power if you drive the gate from the 80V supply. Q9 will have an especially high dissipation. Often high-side drivers need a floating supply. \$\endgroup\$ – Kevin White Dec 10 '19 at 4:28

In theory this works but Pd depends on load capacitance.

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220R is a dummy load

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