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BQ76930EVM: BQ76930

Akilan G
Intellectual 285 points
Part Number: BQ76930EVM
Other Parts Discussed in Thread: BQ76930, BQ78350, BQ76920

Hello Sir, 

I working with BQ76930 EVM and designing custom BMS using BQ78350 and BQ76930. My question is how the charge is detected when charging the batteries using EVM board because I see there is load detection in the BQ76930. From the reference schematics I am thinking there is external circuit to detect the charging to enable the Cell balancing register ON automatically  . It will be helpful for me if you could explains this.

Thank you in advance.

Regards,

Akilan G 

  • 0
    TI__Expert 6085 points
    Hi Akilan,
    Yes, there is load detection circuit designed into the CHG pin of the bq769x0. It is ENABLED, when CHG is LOW. during low-side switching, the CHG pin will be pulled up by the a pack load thru the gate drive network when the DSG FET is OFF.

    Balancing of the cell has to be controlled by the host. On the EVM, p-channel FET external balancing topology. external cell balancing allows higher current in bq76930/40 family. bq76920 EVM has capability of 50mA cell balancing capability without the external network.
    In general, , the bq769x0 family have internal balance FETs controlled by the registers. when Enabled, the internal FETs will close( rds-on ~10ohm) and pull the pins to form a loop with the cell and input resistors. As a reminder, the cell balancing will run from the register setting; Its NOT terminated by LOW VOLTAGE.

    Its the charger's responsibility to to set the proper voltage and current for the pack. bq769x0 *DoesNOT* regulate the charge current; rather ONLY protects from OV.

    Hope this helps you out to get started.