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DRV8962: Body diode characterization

Lenio Cacula
Genius 16130 points
Part Number: DRV8962

I know what I'm asking isn't part of the datasheet, but need to make sure: do we have information of the voltage drop across the body diodes of the MOSFET's based on current and temperature? I see that page 26 of the datasheet uses the value of 1V, but that seems a conservative number to estimate losses only.

Thanks!

  • 0
    TI__Mastermind 24925 points

    Hi Lenio,

    The body diode forward voltage of a MOSFET is typically on the order of 0.8 V to 1.0 V. For example take a look at one of the TI N-channel MOSFETs https://www.ti.com/lit/ds/symlink/csd18533kcs.pdf. We do not have VDS of body diodes based on current and temperature, but it is safe to assume 1V at max. rated current of the integrated FET in the DRV8962. What is the specific concern customer has?  Thanks.

    Regards, Murugavel

  • 0 in reply to Murugavel4637
    TI__Genius 16130 points

    The DRV8962 is getting damaged because of back EMF. Trying to understand alternatives, possibly with additional diodes in parallel. If those diodes in parallel are of lower voltage, the current will circulate outside of the DRV8962 thus protecting it.

  • +1 in reply to Lenio Cacula
    TI__Mastermind 24925 points

    Hi Lenio,

    How was the conclusion made? Could it be possible the back EMF caused voltage pumping and boosted the VM to above the abs max. of the driver which is already pretty high for this device. If VM used is 48V or higher this could happen though.

    Anyways it could be the body diodes are not fast enough. So a Schottky diode across the FETs may improve the situation. I don't see the body diode dropping several volts.

    What is the load used, BDC motor? What is the current rating, supply voltage used? Is PWM drive used and if so what frequency and what duty cycle was used during failure, did it fail when stopping the spinning motor instantly? Can the customer capture VM voltage while stopping the motor if that was the cause for failure? Thanks.

    Regards, Murugavel  

  • 0 in reply to Murugavel4637
    TI__Genius 16130 points

    The circuit has an overvoltage clamp protection.