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BQ21040: USB driven alternative charging for solar powered device

Franz Schellhase
Expert 3605 points
Part Number: BQ21040
Other Parts Discussed in Thread: BQ25570,

Hi team,

One of my customers wants to use BQ25570 for charging a wireless sensor from a small solar cell. For initial charging and in case battery runs low because of lack of solar energy they would like to have the option to charge the sensor via USB using BQ21040. How would you suggest connecting these to make a sturdy system? If you have alternative device suggestions they are are also appreciated.

Thank you,

Franz

  • 0
    TI__Mastermind 19195 points

    Hi Franz,

    This can be done by pulling up the BQ25570 /EN pin to the VUSB of the external powersupply(USB). When a valid VUSB is present it will charge the battery and disable the bq25570 (The PFET between VSTOR and VBAT is off). Note that minimum BQ25570 EN high voltage (to disable the chip) has to be atleast as high as VBAT-0.2. Abs_Max on EN pin is 5.5V

    The battery pins of both devices could then be connected in parallel to the battery.

    Best,