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DRV8353: Gate resistance

Vignesh d
Prodigy 110 points
Part Number: DRV8353

HI,

currently i'm doing mosfet loss calculation for MOSFET in B6 bridge. while calculating switching loss i need to know the the gate resistance of the mosfet. TI suggesting not to use the gate resistance for smart gate driver then how to calculate switching loss of the mosfet. please share any document to help me on this.

thanks,

Vignesh 

  • 0
    TI__Guru 65190 points
    Vignesh,

    Let me check and get back to you.

    Regards,

    -Adam
  • 0 in reply to Adam Sidelsky
    TI__Guru 65190 points

    Vignesh,

    Please check if your FET datasheet lists this info. As we don’t have a gate resistor, the gate pin of the FET itself is the major contributor.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    Prodigy 110 points

    Hi adam,

    Due to the absence of external gate resister in smart driver Rghi and Rglo places major roles.we need to know the value of Rghi and Rglo for DRV8353 with respect to various gate current settings to estimate power losses in Mosfet and loss in the driver. kindly share the those data.

    Thanks,

    Vignesh

  • 0 in reply to Vignesh d
    TI__Guru 65190 points
    Vignesh,

    We don't use pull-up/down switches, ours are FET based as in Figure 32 in the datasheet.

    A close approximation of the power dissipated in those FETs is the IDRIVE current multiplied by the Vds of the FET in question. For the High side, the Vds is the VCP voltage. For the low side, this is the VGLS voltage.

    There is a brief period while the FET is turning on where the RDSON causes a little dissipation. This should be small enough that it can be ignored. After the FET Vgs reaches ~5V, the IDRIVE/VDS dominant region takes over.

    Regards,

    -Adam