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BQ2403x family - When is LDO output active & additional CE questions

Bob Miller76124
Prodigy 30 points

The spec on page 24 states:

Note that this LDO is only enabled when either AC or USB inputs are present. If the CE pin is low (chip disabled) and AC or USB is present, the LDO is powered by the battery. This is to ensure low input current when the chip is disabled.

To confirm then, there will be no LDO output if both AC and USB are not present? Even if the battery is present? That isn't what I expected from the block diagram.

To cover all the conditions, can you correct any incorrect entries below and can you fill in the question marks:

CE USB/AC input BAT input TINY III State LDO output OUT (ignoring Dropout)
H One present Don't Care Active 3.3 At USB/AC voltage
H None Present Sleep 3.3 At battery voltage
L One present Present Standby 3.3 At battery voltage
L One present None ? ? ?
L None Present ? ? ?

Thanks,

Bob

  • 0
    TI__Mastermind 31120 points

    The 3.3VDC LDO output was design to be used with the USB functions.

    Therefore it only made sense to have this on when USB is present.

    The AC and USB inputs can either be configured as USB inputs so if either input is applied, the 3.3V output will be present if not in suspend mode (CE=Low).

    If in suspend mode and there is an input, one still needs USB power and it is run off the battery since USB suspend requires low current.  If no battery then the LDOcan't be powered.

    If one does not have an input, then there is no need for the "USB" LDO.