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BQ76920: Using part without companion controller.

Anton Grivans
Prodigy 160 points
Part Number: BQ76920
Other Parts Discussed in Thread: BQ24610, BQ77904, , TIDA-00449, BQ4050

Hi,

I was wondering if it is possible to use this part for cell balancing only. I want to use a BQ77904 for the per-cell OV and UV protection and a BQ24610 for charging and power source selecting.

In the BQ76920 datasheet, the Figure 8-1 schematic shows that it should be connected to a companion controller, but as I understand, it's only needed to handle fault signals. Can I leave it out and have it working like a cell balance?

Thanks.

  • 0
    TI__Guru 54715 points
    Hi Anton,
    The bq76920 needs a "companion controller" or MCU for various tasks such as 1. Turn on FETs, 2. Set protection faults registers to non-default if desired, 3. Implement desired temperature protection behaviors from the available readings, 4. Implement a cell balancing algorithm, 5. Implement any other or longer protections such as low over current discharge or over current charge, 6. Recover from faults, 7. Calculate any desired capacity, and 8. provide display and/or communication needed by the system.
    The cell balancing mechanism to bypass current around a cell and interleave measurements is in the bq76920, but the algorithm or decision making of what to balance when must be done by the controller.
  • 0 in reply to WM5295
    Prodigy 160 points

    Hi,

    Thanks for the quick reply.  Can you recommend another solution?

    Thanks.

  • 0 in reply to Anton Grivans
    TI__Guru 54715 points
    Hi Anton,
    Since you mention the bq77904 I expect you have 4 cells.
    The bq76920 would handle 4 cells for balancing and protection if you use with a controller, TIDA-00449 may be a reference if you wish to write your own MCU code.
    The bq4050 may also be a good solution with configurable protections and balancing. Use a minimal gauging setup.
    Of course both are more involved than simply installing a part.