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BQ27421-G1: waking from shutdown

Nikolaus Schnitzer
Prodigy 30 points
Part Number: BQ27421-G1
Other Parts Discussed in Thread: BQ25120A

to reduce power consumtion when the battery gets to its EODC voltage of 3.3V our firmware commands the FG in shutdown mode. GPout is pulled up to the system supply voltage (3.2V or 1.8V from bq25120a). When battery voltage further decreases e.g. to 3.1V the system supply voltage is completely shut of, so there is no potential on GPout. If the device is put on a charger the system supply voltage returns to 3.2V. Will this voltage rise on GPout wake the FG from shutdown? can you provide the logic levels for GPout when used as input?

Regards 

Nikolaus

  • +1
    TI__Guru** 105770 points

    Hello Nikolaus,

    I've assigned someone to take a look at this.

    Sincerely,

    Wyatt Keller

  • 0
    TI__Guru 62566 points

    GPOUT (despite its name) also follows the spec in table 7.6.

    From a gauging point of view, your idea is problematic (if not terrible). Shutdown is effectively the same as powering off the gauge so when you turn it back on, the algorithm, which is designed to be adaptive, will start from scratch (and you'll have to configure the gauge again) so a system like that will not allow the algorithm to work efficiently and gauging performance will suffer (greatly).

    If at all possible, please use sleep mode instead. Shutdown is intended for use cases like long term storage (e.g. when a product is being shipped from the factory to the end user or retailer). It's not intended as a mode that gets forced regularly just to save power.