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BQ25890H: BQ25890H REGN output abnormal

Star Xu
Genius 9645 points
Part Number: BQ25890H

Hi

The customer design with BQ25890H, The REGN pin is connect to the CBL_PWR_N of SG865W. It is expected that the device can start automatically wake and start to charging after inserting the USB.

But the problem is when no USB is inserted, REGN pin outputs periodic pulses all the time, causing the device to restart automatically before the normal shutdown process is completed.

Attached the schematic and REGN pin waveform.

4604.CHARGE.pdf

Does the REGN output is normal?

Waiting for your reply.

Thanks

Star

  • 0
    TI__Guru*** 148865 points

    HI Star,

    With VBUS applied, REGN is a dc output voltage with specs below:

    It appears that CBL_PWR_N is pulling more than the REGN pin current limit of 50mA.  Then the charger is retyring to see if the presumed short has been removed.

    Regards,

    Jeff