Patent ID: 8450977

Claim:
A power management system comprising: a first Metal Oxide Semiconductor (MOS) switch coupled between a first power source and a node, said node coupled to a system load; a second MOS switch coupled between a second power source and said node; a driving circuit coupled to said first and second MOS switches and operable for generating a first driving voltage by boosting a voltage of said first power source, and for generating a second driving voltage by boosting a voltage of said second power source; and a control unit coupled to said driving circuit and operable for monitoring statuses of said first power source and said second power source, and for controlling said first driving voltage and said second driving voltage based on said statuses to selectively conduct said first MOS switch and said second MOS switch, wherein said control unit controls said first driving voltage and said second driving voltage to turn on both said first and second MOS switches if said statuses indicate said first power source is in an under-voltage condition, and wherein said second power source provides power to charge said first power source and to power said system load if said first and second MOS switches are both turned on.