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BQ79616-Q1: Equalization circuit fault monitoring

Colin Chen
Intellectual 875 points
Part Number: BQ79616-Q1
Other Parts Discussed in Thread: BQ79616

Does BQ7961 support balanced circuit fault monitoring? How to achieve it?

  • 0
    TI__Expert 8526 points

    Hi Colin,

    Could you please clarify what you mean by balanced circuit fault monitoring?  Are you referring to faults on individual cells during cell balancing?  If so, then yes. 

    The BQ79616 has separated CB and VC pins, enabling the device to monitor for faults and report cell voltages while cell balancing is underway.  The BQ79616 can also check the condition of the internal cell balancing FETs by turning on the balancing FET and comparing the voltage across the FET (through the AUX ADC path) versus the cell voltage (through the Main ADC path).

    Additionally, cell balancing can be stopped when the balancing timer expires, an unmasked fault is detected, or a threshold, such as OV or UV is crossed.  The MCU can also order cell balancing to stop.  Hopefully this helps, and please see the BQ79616 datasheet for more information.

    Best,

    Andria

  • 0 in reply to Andria McIntyre
    Intellectual 875 points

    Thank you for your reply.When I use an external FET for balancing, can I detect faults in the external circuit, such as FET damage, resistance short circuits, etc? How to achieve this detection?

  • 0 in reply to Colin Chen
    TI__Expert 8526 points

    Hi Colin,

    If the external balancing FET fails during external cell balancing, then this will lead to continuous balancing of the cell that has the failed FET.  This will gradually drop the voltage of that cell, and an undervoltage fault will be triggered.

    If the balancing resistor becomes burnt out, then this will lead to a short across the cell when the balancing FET is turned on.  This will most likely also exceed the FET drain to source current rating and damage the FET as well.  This sequence of events should trigger an under-voltage fault right away.

    To avoid this, please ensure that you select a FET and resistor that are rated for the application you want.

    Best,

    Andria