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BQ76930: BQ76930

Pedro DA CUNHA
Prodigy 20 points
Part Number: BQ76930

Hi, 

I am looking for help for the design of a BMS with 8 cells LifePo4, using the BQ7693003DBTR for voltage measurement and balancing and the BQ78350DBTR-R1 for communication.

The problem is balancing. I measured 3mA when the BAL_OK register is ON in BQ Studio. The goal is to have a balancing current of about 150mA

If you need more information, contact me.

Main sheet :

Balancing sheet :

Best regards,

Pedro DA CUNHA

  • 0
    TI__Guru 54715 points
    Hi Pedro,
    As described in the "bq769x0 Family Top 10 Design Considerations" apnote, section 4, "A FET with a defined RDS(ON) at approximately ½ the cell voltage is desired." for the balancing FET. The PMV130ENEA has a Vgsth of 1.6V typical but may be as high as 2.5V, and the RDSON specification is listed only at 4.5V and higher Vgs. See figure 7 of its data sheet, the FET may typically only provide about 1 mA of drain current with about 1.6V or 1.7V Vgs. Contact your favorite FET supplier for a part with a lower Vgsth and defined RDSON at Vgs voltage. A distributor may be helpful in finding a part with a compatible footprint.