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BQ77207: Help understanding application configuration

Susana Aparicio
Prodigy 10 points
Part Number: BQ77207
Other Parts Discussed in Thread: BQ77307, BQ76907

Tool/software:

Hello, I'm designing a battery protection and I'm having trouble understanding the back to back FET configuration of figure 8-1 of the datasheet in bq77207. As I understand, DOUT and COUT are active high that control two NMOS, when a fault is detected the turn on and put the gate of the PMOS to 0, which turns them on. Knowing that, in the normal mode of operation as the voltage of the PMOS vg=vs they would be turned off and wont be able to charge or discharge. I would like to mantain the high side protector FETs if possible.

Am I missing something to understand this application? How can I configure this to work as intended?

  • +1
    TI__Mastermind 42060 points

    Hello Susana,

    For this configuration to work, the part would have to be in active-low configuration. So that if a fault occurs it pulls COUT/DOUT low to turn-off the N-FET. At the moment no current released versions of this device have that capability.

    This protector is most commonly used as a secondary protector meant to flow up a FUSE.

    If you'd like a device that can perform protections and monitoring using FETs, you could look at the BQ76907  device, which has integrated low-side FET drivers for 7s systems. For protector-only devices, you can look at the BQ77307 instead.

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Prodigy 10 points

    Thank you for your answer