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BQ27621-G1 stops responding when the battery is replaced/reconnected

shan shan
Prodigy 135 points
Other Parts Discussed in Thread: BQ27621-G1, BQ27421-G1, MSP430FR5949

Hi,

BQ27621-G1 fuel gauge stops responding to I2C commands(NACKing!) when I disconnect and reconnect the battery. Also I observed I don't see 1.8V LDO output on VDD pin when it is not responding!

If I do power cycling gauge works fine. Can anyone comment on this issue? Since i cant stop the system during the battery replacement suggest me if there is procedure to follow to have robust system!

Thanks,

Shan

  • 0
    Genius 3970 points

    Do you have a pull-up resistor on the GPOUT pin? The bq27621-G1 (or bq27421-G1 as they're based off the same platform) requires a high-value (1.8 MOhm or so) pull-up resistor on the GPOUT pin in order to turn on the LDO regulator. If it's not installed, the gauge won't start up consistently (or in your case, not power on when a battery is reconnected).

  • 0 in reply to en-US
    TI__Mastermind 24870 points

    Thank you Jason for your reply.

    I would like to add:

    Please ensure BIN pin is not shorted to ground. If that pin is shorted to ground it will cause our gas gauge to go into a constant POR state.

    Are you able to share a schematic with us? If so, please add me as a friend on E2E and we can share internally.

    Thanks

  • 0 in reply to Kang Kang
    Prodigy 135 points

            >>>  Do you have a pull-up resistor on the GPOUT pin?

                  I have enabled MSP430FR5949's internal pull-up resistor (47K). I will try having external pull-up and check the system stability.

           >>>   Are you able to share a schematic with us?

                    BIN is not shorted to ground. It has 10k pull-down. please look at my schematics!

     

    BR,

    Shan

  • 0 in reply to shan shan
    Prodigy 135 points

    My schematic misses 1.8Mohm Pull up on BIN pin. After adding it code is more stable.

    Thanks,

    Shan

  • 0 in reply to shan shan
    Prodigy 170 points
    Was there ever a resolution to this problem for you? I am having the same exact issue in my system. In the software I noticed that the device has been removed and when it is reinserted I issue the unseal the command. The problem is that the device NACKs the command so I can never speak to it again unless I power down the system and power it back up again.

    Thanks,
    Dave