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BQ76952: FUSE Pin behavior after permanent fail occurs and FUSE commands fuse to open

Alec Fremier
Intellectual 330 points
Part Number: BQ76952


Tool/software:

I am configuring the BQ76962 FUSE pin to drive a NFET to blow a fuse, very similar to the architecture shown in the data sheet. Similarly, the device will be configured to enter DEEPSLEEP when a PF occurs, and the device will write PF status to OTP. How does the FUSE Pin respond If the pack wakes again? Will it continue to drive the FUSE pin HIGH?

Similarly, if a PF fail has occurred, is FUSE continuously driven HIGH until DeepSleep/Shutdown is entered?

  • 0
    TI__Mastermind 18915 points

    Hello Alec,

    Thank you for your patience. 

    Alec Fremier said:
    How does the FUSE Pin respond If the pack wakes again? Will it continue to drive the FUSE pin HIGH?

    If the device wakes up from DEEPSLEEP again, because it already blew the FUSE earlier when the PF triggered for the Fuse Blow Timeout time from before DEEPSLEEP, I do not think it would attempt to drive the FUSE pin HIGH again unless the timeout is potentially set to 0. This will need to be tested to confirm if that is the case or not. 

    The status of the FUSE pin is provided in the 0x12 Battery Status[FUSE] bit, and the 0x001D FUSE_TOGGLE() subcommand can be used to toggle the state of the FUSE pin drive as well. 

    Alec Fremier said:
    Similarly, if a PF fail has occurred, is FUSE continuously driven HIGH until DeepSleep/Shutdown is entered?

    When the FUSE pin is asserted to blow the external fuse, it will only stay asserted for a length of time set by the Settings:Fuse:Fuse Blow Timeout configuration register. If this value is 0, it will blow output indefinitely (no timeout).

    Best Regards,
    Alexis