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BQ76920: VC3-VC4 correct connection for 4-cell configuration

DudeFromRiga
Intellectual 305 points
Part Number: BQ76920

Hello, 
We are using BQ76920 for 4-cell battery pack. 
As stated in datasheet Table 8-1. "Cell Connections for bq76920", VC4-VC3 is short.

There are 2 ways how we understand it - please, see attached pictures.


Are these schematics functionally equal? - what is the behaviour of pin VC4 and VC3 in this case: 1) during balancing ;  2)during measurements?

  • 0
    TI__Mastermind 19580 points

    Hi GuyFromRiga,

    For a 4-Cell configuration, your 2nd schematic has the proper implementation because it is the input pins of the device that need to be shorted which eliminates the passives as you have crossed out.

    1) During cell balancing the behavior is left to the host controller.

    2) During measurements, there is a minimum UV threshold that has to be met by the ADC for its value to qualify. This value is 0x0518 of the ADC and it is located on Table 6.5 "Electrical Characteristics" on p16 of the datasheet. Via the conversion on section 7.3.1.1.2, 0x0518 is roughly 500mV. Since the cell is shorted, its value will be below this threshold and will not be used.

    Best Regards,

    -MZ

  • 0 in reply to Marcoo Z
    Intellectual 305 points

    Thank you for fast reply, MZ!
    That's exactly what I wanted to know =)