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BQ25570: Managing BQ25570 when VIN is absent

Swapnil Sayan Saha
Prodigy 70 points
Part Number: BQ25570

I am designing an underwater energy harvesting circuit using BQ25570. As per the datasheet, the device requires 0.6V for cold start and at least 0.1V for normal operation.

I was wondering how to make the chip operate (at least the buck portion since that supplies voltage to the system) when the energy harvesting circuit is not generating any energy (VIN < 0.1V) but the battery still has sufficient voltage to power the sensor node. 

  • 0
    TI__Guru*** 143880 points

    Hi Swapnil,

    The BQ25570 VOUT buck functions as long as its input from VSTOR>UVLO which is 2.2V.  The PFET between VBAT and VSTOR auto opens, preventing the battery from powering the charger and buck if the battery voltage drops below 2.2V.

    Regards,

    Jeff