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Original question:

BQ25618：BQ25618 VSYS_OVP

BQ25619EVM：BQ25619 EVM

user5781628
Intellectual 970 points
Part Number: BQ25619EVM
Other Parts Discussed in Thread: BQ25619, BQ25601

Hi TI team,

 I buy a BQ25619-EVM from ti-store.

After USB plug-in, I found the SYS voltage is 4.2V without battery connection. 

Due to without battery connection(VBAT=0<VSYS_MIN), why the SYS voltage is not the VSYS_MIN(3.68V) ?

Thanks!

BR

  • 0
    TI__Guru 51421 points

    Eleven,

    The device does not have battery detection function. When battery is not connected and charging is enabled by default, the device tries to regulate VBAT to charging voltage (VREG, 4.208V default) then terminate charging. After certain time, VBAT will drop below the recharge threshold and the device charges VBAT to charging voltage (VREG) again. So the charger status indicates between charging in progress and charging complete, so STAT pin blinks. Higher VSYS ripple is also related to the behavior. If charging is disabled with /CE pin or by register bit, the device does not charge and STAT pin should not blink, VSYS is 150 mV above the minimum system voltage (VSYSMIN, 3.5V default) as well.

    Please visit e2e.ti.com/.../890624 for I2C controlled BQ2560X: Schematic Review and PCB Layout Design Tips. BQ25619 is similar to BQ25601.

    Please visit https://e2e.ti.com/support/power-management/f/196/t/875386 for FAQs. The principles are the same.

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Intellectual 970 points

    Thanks, Ning.

    BR

    Eleven