MP18851 - Dual High Side Mosfet

DC-DC Power Converters
1

two questions:

  1. Can i use MP18851 to drive two High Side Mosfets ,I’m Planning to use two MP18851 to drive 4 Mosfets for a 3 level buck converter.

  2. How can i determine how fast can my driver switch? my Mosfets handle up to 300MHz switching but will my driver be able to do such switching ?

    Schematic :

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Hello, apologies for the delayed response on this request. To answer these questions:

  1. Yes, you should be able to use 2x MP18851 gate driver ICs for 4x MOSFETs as long as each channel is referenced correctly and is fully isolated (which this solution appears to be).
  2. The MP18551 is ok for hundreds of kHz to the low MHz of high side switching. However, designing around 300MHz of hard switching and assuming FET speed alone doesn’t make sense here. Also sharing driver references across switching nodes isn’t recommended. Fundamentally, you can see how the gate driver switching speed fmax = Idrv / Qg where:
  • Idrv = peak source/sink current, in this case 4A
  • Qg = total gate charge of Vgs

Hopefully this offered some insight.

Best,

Krishan