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DRV8873-Q1: Output Current through Body Diode of Internal FET

Shinichi Yokota
Genius 9715 points
Part Number: DRV8873-Q1

Hello,

When an output current runs through a body diode of DRV8873S-Q1's internal FET, when the DRV8873S-Q1 is in a state of brake or slow decay, for example, will the DRV8873S-Q1 detect the current by the current regulation and/or OCP functions?

Best regards,
Shinichi Yokota

  • 0
    TI__Guru 56650 points

    Yokota-san,

    DRV8873S-Q1 can only detect OCP when the FET is on.

    For current regulation, if the sense resistor current is higher than the ITRIP level, the device keeps the high side FET off. In this case, DRV8873S-Q1 still monitors the current.

  • 0
    TI__Guru** 114905 points

    Hi Yokota-san,

    The OCP function works when current is flowing from the FET drain to source.

  • 0 in reply to Rick Duncan
    TI__Genius 9715 points

    Rick-san,

    Perhaps, I may not understand the state of H-bridge correctly when the DRV8873S-Q1 is in a brake (or slow decay) state. Will the DRV8873S-Q1 turn on high-side FETs of both half-bridges and will the output current not run through a body diode?

    If it's correct, will the IPROPIx pin on the side where the current flows from source to drain of the internal high-side FET show 1/1100 of the current? I don't think so because if it's true, the IPROPIx pins will show double the output current in a brake (or slow decay) state when the pins are tied together.

    Best regards,
    Shinichi Yokota

  • 0 in reply to Shinichi Yokota
    TI__Guru 56650 points

    Yokota-san,

    Since I signed myself to this post. Rick may not see it. Let me continue answer your question.

    Yes. If the high side FETs are both turned on, the high side FET's drain to source current is measured and shown up to IPROPRIx pin.

    The current sense circuit senses the current flowing from the FET drain to source, not source to drain.