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Original question:

BQ25792: DESIGN ISSUE

BQ25792: chip charge & discharge issue

Yangyang Zou
Prodigy 120 points
Part Number: BQ25792
Other Parts Discussed in Thread: BQ28Z610

HI ,

        I have two questions, please help me . Thank you！

       1、We actually measured and found that the VBAT voltage measured when charging with the adapter plugged in would be several hundred mV higher than the VBAT voltage measured when the adapter was unplugged. Is this normal? And it can also be reflected through registers on the BQ28Z610 chip, as shown in the following figure，or can we read the corresponding value through the charger chip itself for our judgment?

         

      2、After fully charging (STAT LED light goes off, charging current reads 0), unplug the adapter and quickly plug it in. The chip will continue to charge               (STAT LED light stays on, charging current reads 0). Is this normal?

         

Regards,

Yangyang

  • 0
    TI__Guru**** 166696 points

    Hi Yangyang,

    Regarding 1, if input power is applied and charge is enabled, there is current flowing.  Any resistance between the charger BATP sense pin and the BQ28Z610 's sense pin creates a voltage drop. So, the voltage sensed at the charger's BATP pin will likely be higher that sensed by the BQ28Z610.

    Regarding 2, when the adapter is removed and reapplied, a new charge cycle starts but should quickly terminate once the charger sees V(BAT)=BATREG and ICHG<ITERM assuming termination is enabled.

    Regards,

    Jeff