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BQ76930: Conditions disabling internal LDO

Christina Lim
Expert 6305 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ76940,

Hi,

May I confirm the behavior of the internal LDO on BQ76930x under SHIP mode and the possible conditions which internal LDO be shut off?

Also is there a min duration for Vshut voltage to stay below the threshold before the device trigger a power on reset?

Thanks,

Christina

  • 0
    TI__Guru* 81034 points

    Hi Christina,

    The LDO is powered off during SHIP mode. SHIP mode only powers the very minimum circuits needed to detect the Boot signal on TS1. The LDO can be Shut off if one of the power voltages to the device falls below POR.

    There is no minimum duration specified in the datasheet for the device to go into POR, but it is recommended to never allow the device to go into this state after it is in Normal mode. SHIP mode should only be entered by sending the SHIP mode settings via I2C. There is this Caution statement in the datasheet:

    DO NOT OPERATE THE DEVICE BELOW POR. When designing with the bq76940,
    the intermediate voltages (BAT–VC10x), (VC10x–VC5x), and (VC5x–VSS) must each
    never fall below VSHUT. When this occurs, a full device reset must be initiated by
    powering down all three intermediate voltages (BAT–VC10x), (VC10x–VC5x), and
    (VC5x–VSS) below VSHUT and rebooting by applying the appropriate VBOOT signal to
    the TS1 pin. When designing with the bq76930, the intermediate voltages (BAT–VC5x)
    and (VC5x–VSS) must each never fall below VSHUT. If this occurs, a full device reset
    must be initiated by powering down both intermediate voltages (BAT–VC5x) and
    (VC5x–VSS) below VSHUT and rebooting by applying the appropriate VBOOT signal to
    the TS1 pin.

    Best regards,

    Matt