Patent ID: 7538452

Claim:
A power-saving circuit applied in a portable electronic device that selectively receives an external voltage or a battery voltage, the power-saving circuit comprising: a voltage input module configured to receive and output the external voltage or the battery voltage, and output a first enable signal when receiving the external voltage; a power switch configured to output a second enable signal in response to an operation by a user; a switching module electrically coupled to the voltage input module and the power switch, and configured to receive the first or second enable signal to determine whether or not to close the switching module; a voltage conversion module electrically coupled to the switching module, and configured to receive voltage from the voltage input module when the switching module is closed, convert the voltage received from the switching module into a working voltage, and output the working voltage to the portable electronic device; and a control chip electrically coupled to the power switch, and configured to receive the second enable signal and output a maintain signal to the switching module for maintaining the switching module in a closed state.