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DRV8872-Q1: Feedback current protection

Christian Edhofer
Prodigy 100 points
Part Number: DRV8872-Q1
Other Parts Discussed in Thread: DRV8872

Hi there,

has the DRV8872-Q2 any protection against feedback currents (e.g. loss of supply voltage)?

Or is it recommended to use external components for protection on the output paths?

Thank you very much in advance.

Best regards,

Christian Edhofer

  • 0
    TI__Guru 56650 points

    Christian,

    Would you give more detail about "against feedback currents (e.g. loss of supply voltage)"?

    What is the feedback current? How is it related to loss of supply voltage?

  • 0 in reply to Wang5577
    Prodigy 100 points

    Hi Wang,

    Thank you for your quick response and sorry for not providing more details in the first place.

    This scenario refers to tests of our ECUs which we have to perform.

    Loss of supply voltage means in that case, that there is a broken connection of the battery voltage to the ECU but GND connection is still there or vice versa.

    If there is a broken connection of the battery voltage and at the same time a short circuit to battery voltage at one of the DRV8872's output pins, the ECU can get supplied via this output path. In that case, a current flows through the device's output pin via the body diode of the High Side MOSFET to VM and then to other circuits of the ECU.

    The other case would be, a broken connection of GND and at the same time a short circuit to GND. Then the Low Side MOSFET would be affected.

    In both cases, it is important that the device gets not damaged through this "feedback current".

    So, my question is:

    • What is the maximum power dissipation of the integrated MOSFETs in reverse direction?

    Best regards,

    Christian Edhofer

  • 0 in reply to Christian Edhofer
    TI__Guru 56650 points

    Christian,

    Thank you for explanation. The feedback current could go through the power FET's body diode. This is the worst case.

    In general, the power FET's body diode can handle a very high current. DRV8872 datasheet doesn't have that spec. But, the peak current capability is higher than the 6.4A peak Iocp current. For a long run, the thermal performance requirement decides the maximum feedback current.

  • 0 in reply to Wang5577
    Prodigy 100 points

    Thank you very much for your answer.

    Best Regards,

    Christian