POWER SUPPLY CONTROL DEVICE AND METHOD

摘要

Apparatuses and methods for controlling a power supply are provided. First power supply selecting circuit selects a higher voltage from USBIN and ACIN to be first output voltage; first LDO decreases the first output voltage to second output voltage, and closes self-start circuit after receiving reference voltage; second power supply selecting circuit selects a higher voltage from second output voltage and VBAT to be third output voltage; second LDO supplies the third output voltage as the first input voltage to reference circuit; reference circuit outputs the reference voltage according to first input voltage; second LDO closes self-start circuit after receiving the reference voltage; voltage detecting circuit supplies an enable signal to second LDO when determining that USBIN orACIN reaches a threshold voltage according to the reference voltage; and second LDO provides the first input voltage to reference circuit after receiving the enable signal.