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DRV8839 NFET body diode

Andrew Brown80
Prodigy 20 points
Other Parts Discussed in Thread: DRV8839

Hello,

I am looking at an application where the DRV8839 will be used as a full bridge. The application also requires full passive rectification (all FETs off).


As there is no specification for the NFET body diodes on the data sheet I am not confident in using the device without adding external diodes. Would TI be able to  provide data for the body diodes?


Thanks.

Andrew

  • 0
    TI__Guru** 114905 points
    Hi Andrew,

    Will you be using passive rectification during normal operation, or only during abnormal conditions?

    The body diodes are designed to carry the same amount of current as the FETs, although less efficiently. Schottky diodes are more efficient when using passive rectification.

    If you are concerned, adding a footprint for external diodes is a good way to evaluate your options.

    This assumes space is available on the board.
  • 0 in reply to Rick Duncan
    Prodigy 20 points
    Hi Rick,

    Thanks for your reply. Passive rectification will be one of a few normal operating modes for the device. The diode current will be very small compared to the specified FET current in this mode <10mA, so from your reply I expect there will be no issues. Do you know what the typical forward voltage drop would be?

    As you suggest my board space is limited, so using the on board diodes would be the preferred option.

    Regards, Andrew
  • 0 in reply to Andrew Brown80
    TI__Guru** 114905 points
    Hi Andrew,

    For low currents (~.5A) , the typical diode voltage is approximately 0.7V. For higher currents (up to 2A), the typical diode voltage can rise to 1V.