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I'm using a gate drive transformer to drive w45nm60 mosfet. And this circuit for increase gate turn off: enter image description here

But it seem to turning off the gate by throwing excess current from gate to source.

So I want to use negative source taken from gdt (which it wasted every half cycle) to turning gate off. Here is the schematic: enter image description here Will it work? How to limit negative voltage output to about 5v or less (to reduce gate discharge when returning on at next cycle) by adding zener diode?where the best place to add it? Is anybody have a circuit which can turning gate off when Vgs supply start to fall (or before dead time)?

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But it seem to turning off the gate by throwing excess current from gate to source.

You seem to be missing one valuable point; that is exactly what is meant to happen to turn the MOSFET of more quickly; it removes charge quickly and that means taking a surge of current for a short time period. That's how it works!

Your proposed alternative circuit won't work as you expect (C1 will acquire charge and after a few cycles the circuit will be ineffective). So, I would strongly urge you to simulate this.

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  • \$\begingroup\$ So can C1 replaced with external supply? I want to give negative supply(or few volts below zerro) to gate. \$\endgroup\$
    – Hida
    Nov 28, 2020 at 12:18
  • \$\begingroup\$ Yes it can @Hida but it really needs you to simulate it. \$\endgroup\$
    – Andy aka
    Nov 28, 2020 at 12:21
  • \$\begingroup\$ @Hida are you done with this question now or do you want to leave a comment to ask for more information. If you are done then read this. It's also good practice to upvote answers that are helpful and to accept the best answer to a given question. This ensures that you continue to receive help whilst not gaining any reputation as being mean. This applies to all questions that have actually received an answer but, of course, some answers may not make sense so that is why I ask you to leave a comment in order to resolve any problem. \$\endgroup\$
    – Andy aka
    Dec 3, 2020 at 9:41

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