SNVSA28 December 2014 LP8731-Q1
PRODUCTION DATA.
The device is designed to operate from an input voltage supply range between 2.8 V and 5.5 V. This input supply may be a battery or regulated source with sufficient low internal resistance such that it is able to deliver the maximum input current and maintain stable voltage without significant voltage drop during start-up and at load transient conditions. Additional bulk capacitance may be necessary should the supply source is located more than five centimeters away from the LP8731-Q1.
All power inputs should be tied to the main VDD source (for example, battery), unless the user wishes to power it from another source. (that is, external LDO output).
The analog VDD input pins power the internal bias and error amplifiers, so they should be tied to the main VDD. The analog VDD inputs must have an input voltage between 2.8 and 5.5 V, as specified in the General Electrical Characteristics table.
The other input pins (VINLDO1, VINLDO2, VIN1, and VIN2) can actually have inputs lower than 2.8 V, as long as it is higher than the programmed output (0.3 V, to be safe).
The analog and digital grounds should be tied together outside of the device to reduce noise coupling.