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BQ24292i-without battery connected

Bao Shao
Prodigy 40 points
Other Parts Discussed in Thread: BQ24292I, BQ24192

Hi,

We developed one board with BQ24292i charger, one usage: without battery connected, we need the board to power up, how to do it?

Regards,

Bao Shao

  • 0
    TI__Expert 8690 points
    Hi Bao,

    You can power up the board, but you need that the load current at start-up be less than 100mA (allow 1s to make sure). Since you don't have a battery, you need to wait for the system voltage to be above 2.2V. This is explained in page 14 section 8.3.1.4 of the datasheet. You can use a load switch with a delay or have some sort of low power start-up mode.

    Thanks,
    Steven
  • 0 in reply to Steven Bangdiwala
    Prodigy 40 points

    Hi Steven,

    We added 1s delay in the PMIC FW, that is when PMIC get VSYS power from charger, it delay 1s to send power rails out.

    But the system still can not power up without battery connected. The  VSYS power voltage is about 4.2V, but it has low pulse periodly and cause the system power down frequently. Need your comments and support.

    Thanks,

    Bob Shao

  • 0 in reply to Bao Shao
    TI__Expert 8690 points

    Bao,

    Your problem could be an input current limit issue. If your input source can support 1.5A output, have PSEL low so that default input current limit is 1.5A. Can you read I2C address 0x00 and 0x08 and give me the readings when VSYS gets powered down?

    Thanks,
    Steven

  • 0 in reply to Steven Bangdiwala
    Prodigy 40 points

    Hi Steven,

    Thanks a lot for your support.

    When have PSEL pull low, the board can boot to BIOS screen without battery before booting into Android OS,but at the time the board shut down suddenly.

    The serial port showed the log:

    [    2.392593] bq24192 13-006b: HW termination happened.

     

    We can not read I2C address 0x00 and 0x08.

    What's the max power loading of VSYS for the charger to support when no the battery connected?

     

    Regards,

    Bob

     

     

  • 0 in reply to Bao Shao
    TI__Expert 8690 points
    Bob,

    The max power for VSYS would be 5V(adapter voltage)*1.5A(input current limit)*~.93 (efficiency) = ~7W. Or 4.2V/1.67A output. If you want more VSYS power, you need to increase input current limit by writing to IINLIM in REG00 through I2C.

    Thanks,
    Steven
  • 0 in reply to Steven Bangdiwala
    Prodigy 40 points

    Hi Steven,

    We reworked the board:pull the BQ24292i pin2(PSEL) to low and pull pin10(ILIM) to GND directly.

    And write 111 to IINLIM in REG00 through I2C. Is that ok to set the max input current limit to 3A?

    By the actions mentioned above, we have managed to boot the board to Android, but the board will shutdown after a while.

    Is the max power for VSYS would be 5V(adapter voltage)* 3A(input current limit)*~.93 (efficiency) = ~13.95W  ?

    What's the max power the BQ24292i can afford to the system ?

    Can we increase the input power voltage to increase input power?

    Regards,

    Bob