Patent ID: 8149556

Claim:
A power adapter for an electronic device, comprising: a power interface to receive an alternating current (AC) voltage signal from a power source and output the AC voltage signal; an alternating current to direct current (AC/DC) converter to receive the AC voltage signal and convert the AC voltage signal into a first direct current (DC) voltage signal; a power converting circuit to receive the AC voltage signal from the power interface and convert the AC voltage signal into a second DC voltage signal for the electronic device; a microprocessor to receive the first DC voltage signal from the AC/DC converter and to be connected to the electronic device to receive a computer state signal from the electronic device in response to the electronic device being powered off or working with a battery in a determined charge state, and output a control signal according to the computer state signal; and a relay connected between the power interface and the power converting circuit, and connected to the microprocessor, wherein the microprocessor outputs the control signal to drive the relay to disconnect the power interface from power converting circuit, wherein the power adapter further comprises a switch connected between the power interface and the power converting circuit via the relay, the switch is a single-pole-double-throw switch comprising a pole connected to the power interface to receive the AC voltage signal, a first throw directly connected to power converting circuit, and a second throw indirectly connected to power converting circuit via the relay.