Patent ID: 8441157

Claim:
A power supply system, for enhancing a duration of portable use of a portable electronic device, comprising: a transformer, for receiving an external alternating current (AC) power, to transform the external AC power into an external direct current (DC) power; a battery, for storing electric energy, to provide a battery power; a selection module, for outputting the external DC power or the battery power according to an electrical connection status between the external AC power and the transformer; a first-stage DC conversion module, coupled to the selection module, for converting power provided by the selection module into a first DC power; a plurality of second-stage DC conversion modules, each for converting an input power into a second DC power; and a switching module, coupled to the external DC power, the battery power, the first-stage DC conversion module and the plurality of second-stage DC conversion modules, for switching to output the battery power or the first DC power as the input power of each of the plurality of second-stage DC conversion modules according to the external DC power.