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LM5021: Gate resistor selection

Nobuhiko Wasa
Intellectual 930 points
Part Number: LM5021

Hi team,

My customer is asking us about gate resistor selection for LM5021.
Datasheet mentions that "A general range of values to consider would be 0 Ω to 10 Ω for this converter".
1. Is there any upper limit of resistance selection?
2. Is there issue other than power dissipation for the case of 22 ~ 100 ohm?

Thanks,
Nobuhiko Wasa

  • 0
    TI__Mastermind 47685 points

    The gate resistor value affects the MOSFET turn-on speed, then affecting power losses, and EMI, etc. If the value is too big, the MOSFET cannot turn-on fast enough which will affect the switching frequency selection - you cannot design switching frequency with a high value if that is desired then the MOSFET cannot controlled as expected - you may see the MOSFET becomes very hot and the output voltage may not be in regulation, or even you converter cannot start.

    I suggest you test and find out to get a proper resistor with starting point 0 to 10-ohm.