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BQ76940: questions cell balance（one chip or stacked bq769x0）

user5358728
Prodigy 20 points
Part Number: BQ76940
Other Parts Discussed in Thread: TIDA-01093

Hi Matt，Willy，

    I have a question about bq769x0 cell balance. As I know the host controller like msp430 can set/reset the Cellbal1，2，3 to control cell balance.   If host controller do nothing on the registers，will 769x0 do cell balance automaticly？（controlled by internal digital core？）

     Or does host controller must have a algorithm to achieve cell balance？

     what about the stacked bq769x0（like tida-01093），do I need algorithm to balance the cells which controlled by the same bq769x0. and also need extra algorithm to balance the two groups controlled by different bq769x0？

       I have read the FAQ and 10concern but havent found the answer.

       thanks

  • 0
    TI__Guru 54715 points

    Hi User,

    1. The BQ769x0 does not balance automatically, the host must control the algorithm.  Also be aware that the BQ769x0 does not timeout the balance registers, so the host must also stop balancing, not just start it.

    2. Yes, the host controller must have a balance algorithm

    3. With a stacked design the host will know all the cell voltages and decide which cells to balance.  You might say it will just have more voltage inputs to its algorithm and more destination registers for control.  If you have a system with multiple MCUs where there is one for each BQ769x0 and one which talks to both of them, you would need 2 levels of algorithms: The first level would be to balance the cells of the BQ769x0 controlled by its host, the second level to balance between the groups.