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BQ78350-R1A: Fault handling of BQ78350-R1A and Bq76930

KIM
Intellectual 550 points
Part Number: BQ78350-R1A
Other Parts Discussed in Thread: BQ76930, BQ78350-R1, BQ78350

Hi,

I am thinking to use both BQ78350-R1A and BQ76930 for the BMS design. I am not sure about the fault handling by BQ78350-R1A and BQ76930 combination.

Based on the BQ76930 data sheet, there are integrated hardware protections in BQ76930.

My questions: If there is fault (e.g. overvoltage), is the BQ78350-R1A or BQ76930 turn off the CHG/DSG FET? Or BQ78350-R1A is used to set the BQ76930 fault threshold only and BQ76930 will turn off the FET (e.g turn off CHG FET for OV fault)?

For permanent failure, if the cell voltage is > SOV threshold, BQ78350-R1A will send the command to BQ76930 to turn off all the CHG, DSG & PCHG FETs. Am i right?

Thansk!

.

  • 0
    TI__Mastermind 42070 points

    Hello Kim,

    The BQ76930 requires a companion host, like the BQ78350-R1A to control the CHG/DSG FETs for protection and to recover from faults. The BQ78350-R1 would read data from the BQ76930 to control protections.

    Yes, you are correct, the BQ78350-R1A would let the BQ76930 to turn of all FETs in permanent failure.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Intellectual 550 points

    Hi Luis,

    BQ76930 has the following hardware protections. BQ78350 has more fault protection based on the measurement received from BQ76930.

    – Overcurrent in Discharge (OCD)
    – Short Circuit in Discharge (SCD)
    – Overvoltage (OV)
    – Undervoltage (UV)

    Can i say that BQ78350 will react to the above faults prior BQ76930 take action if the threshold is set correctly? For example, the cell OV threshold is set to 4.25V for BQ76930 and cell OV threshold is set to 4.2V for BQ78350. whenever any cell voltage is > 4.2V, BQ78350 will react and send command to BQ76930 to turn off the charging FET. In case BQ78350 is faulty, BQ76930 will be the secondary protector to turn off the charging FET if cell voltage > 4.25V.

    Is my understanding correct?

    Thanks!

  • 0 in reply to KIM
    TI__Mastermind 42070 points

    Hello Kim,

    Yes, however, the BQ78350 is required in order to recover from these protections. So if the BQ78350 is faulty, the BQ76930 would not be able to recover from the protections.

    Best Regards,

    Luis Hernandez Salomon