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BQ27621-G1 SCA/SCL/GPOUT pulled up to Vbat?

Barry Klein1
Intellectual 610 points
Other Parts Discussed in Thread: BQ27621-G1

I am working on a project that has the BQ27621-G1 SCA/SCL and GPOUT pins pulled up via 10K resistors to Vbat (single cell 3.7-4.2V). We see the chip overcurrent/fail if Vbat connected to the board.  The spec calls out these to be pulled up to VDD off the chip source pin.  Is this the cause of the failure and could you explain the details of why - if so? BIN pin is pulled down 10K to ground. Caps on VDD and BAT pins correct.

  • 0
    TI__Expert 3385 points

    Hi Barry,

    It is recommended that you do not exceed 3.6V for external pull up voltages including GPOUT. Exceeding absolute maximum (6V) will cause damage to the IC, but please use the recommended operating conditions(no more than 3.6V) as a basis for design. Please see datasheet below.

    Best,

    Justin

  • 0 in reply to Justin Erfan
    Intellectual 610 points

    This spec snippet is weird because Vbat is never normally 3.6v - but more likely 3.7-3.8V with charging at 4.2V. Can you find out more? BTW, cause of our chip failure determined to be Vbat reversal. Still our pull-ups go to potentially 4.2V.

  • 0 in reply to Barry Klein1
    TI__Expert 3385 points

    Hi Barry,

    This will depend on the battery's manufacturing process, so the nominal voltage may vary. Nonetheless, the pin is not intended to be powered from Vbat. As you have noted, below are our layout recommendations defined in our datasheet.

    Best,

    Justin