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BQ76920: External balance allowing for adjacent cell balance

FJ
Intellectual 360 points
Part Number: BQ76920

I am considering controlling the external balancers directly from the MCU and leaving the balancing off on the BQ76920. My goal, is that using the attached circuit will allow me to be able to balance all or adjacent cells at the same time without effecting the voltage readings of the BQ76920. Will attached design allow me to do this?

  • 0
    TI__Guru 54715 points

    Hi FJ,

    It seems the general concept should work.  A few comments:

    Your pull up for the BJT collector may need a voltage divider to protect the FET gate from its abs max.  A zener may be needed on the gate for transients.

    The pull down on the Si FET gate should likely go to CV4 to avoid abs max on the gate voltage.  Again consider transients possible on the gate voltage and if a resistor is needed to the drain of the FDV FET.

    The interconnect to the cells likely has some resistance, so when balancing you may see some small  movement in the cell voltages, but it should not be large and you should not have the settling time limitations of balancing controlled by BQ76920. 

  • 0 in reply to WM5295
    Intellectual 360 points

    Thanks for the suggestions.  Will do!