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BQ76930: Cell balancing query

Shreenidhi Patil
Expert 3936 points
Part Number: BQ76930

My customer is designing  on 10s battery pack solution using bq76930

He is now trying to implement cell balancing

And he has the following question below

 

We are using external resistive cell balancing circuit which is derived from BQ chip.

In BQ datasheet, it is written that “total duty cycle devoted to balancing is approx. 70% per 250ms”

My questions are:

Do we need to control this duty or it is controlled by BQ itself?

We are only using CELLBAL1, CELLBAL2 and CELLBAL3 register for cell balancing . Are they sufficient for configuration?

 

Can you please help me with this query 

  • 0
    TI__Guru 54715 points

    Hi Shreenidhi,

    The bq76930 provides the duty cycle of the balancing FETs to allow continued measurement during balancing.  You might look at the application note Embedded Scheduler in Cell Battery Monitor of the bq769x0  section 2.2.  You do not need to control that duty cycle beyond setting the appropriate bits in the CELLBAL registers. 

    CELLBAL1, CELLBAL2 and CELLBAL3 are the cell balancing registers for the family, each controls the cell balance for group identified.  CELLBAL1 and CELLBAL2 control the applicable bits for the bq76930. The host must implement an appropriate algorithm to set and clear bits in the registers at the proper times to achieve the desired cell balance.