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BQ25890: BQ25890 some times not charging or supply power for VSYS.

Feng Xu
Intellectual 390 points
Part Number: BQ25890

Hi,

     I have used BQ25890 in my device, and 20 devices are used in my team.

     Sometimes, occursionly, the BQ25890 is not charging or supply power for VSYS, while the VBUS is good.

     Here, I have read all the registers out:

     I think all the registers are alright, the VBUS is good and is 5.3V. But it is not charging or supply power. Why?

     Thank you.

Frank

  • 0
    TI__Mastermind 31630 points

    Hi Frank, 

    Based on the register values you provided the reason your device is not charging while VBUS is good is because you have REG00_EN_HIZ = 1 (REG00 bit 7). With HIZ mode enabled the REGN LDO is off. The switching FETs do not function in HIZ mode and the battery will power the output system. REG0E_BATV and REG0F_SYSV show the battery is powering the system at 4.164V. The rest of your register settings look alright.

    Write via I2C to REG00 to set EN_HIZ to 0. Once HIZ mode is disabled your Vbus input will charge the battery and supply power to Sys.

    Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Intellectual 390 points

    Hi Garrett,

         Thank you.

         But in my code, I didn't make settings to REG00.

         And the default value of EN_HIZ is 0. Does anything else will make EN_HIZ to 1?

         Regards,

    Frank

  • +1 in reply to Feng Xu
    TI__Mastermind 31630 points

    Hi Frank, 

    Section 9.2.3.1 of the BQ25890 datasheet states the device conditions that will enable HIZ mode other than setting EN_HIZ to 1. Although when the device is in HIZ mode due to no VBUS present EN_HIZ still reads 0.

    Also something else to be aware of, when the watchdog timer expires the device's registers will reset to default values. If EN_HIZ is set to 1 and the watchdog timer is disabled, the IC remains in HIZ state until it is set back to 0 through I2C or VBUS is removed and replaced.

    Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    Intellectual 390 points

    Hi Garrett,

        Thank you.

    Frank