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Original question:

BQ2970: BQ29700 not turning on pass FETs

BQ2970: Initial fault condition on battery connection

Angus Thomson
Prodigy 30 points
Part Number: BQ2970

It seems that when a battery is first connected to the BQ2970 its output is sometimes disabled due to an apparent fault condition. The wording in the datasheet specifically says "the discharging circuit might not be enabled", and the response to a previouos question also indicates there is some uncertainty. In my case this is actually a desirable feature, as it allows us to connect a battery and ship the unit without any devices on the board pulling current.

However it seems like this behaviour will not happen 100% of the time. Can TI provide a figure for how often this may occur, or alternatively, is there a way to force this condition to occur 100% of the time? That way we don't need to impement our own shipping mode!

Thanks

  • 0
    TI__Mastermind 42060 points

    Hello Angus,

    Typically when the battery is first connected the discharging circuit is disabled. This typically will be the case when the battery is first connected.

    However, we cannot guarantee this will be the case every time, as we do not know exactly how the battery is assembled. We have not characterized how often or when it could happen.

    A possible way to ensure the circuit remains disabled is to  have a temporary dummy load on the PACK+/PACK- terminal. Usually to enable the circuit, V- and Vss needs to be shorted, so this "load" may be able to keep the device OFF. 

    Best Regards,

    Luis Hernandez Salomon