Patent ID: 7723870
Filing Date: 2010-05-25
Classification: G06F,H02J

Abstract:
1. A power switch system for selectively providing power from a primary power source and a secondary power source to an electronic device, the primary power source and the secondary power source being independent from each other, the power switch system comprising: a detecting module connected to the primary power source, a selecting module connected to an output terminal of the detecting module, the primary power source, and the secondary power source, and outputting power from the primary power source to the electronic device if the primary power source is available; the detecting module being configured for determining whether the primary power source is available for the electronic device and generating a switch signal if the primary power source is unavailable, and the selecting module outputting power from the secondary power source to the electronic device in response to the switch signal, wherein the selecting module comprises a first transistor, a second transistor, and a third transistor; the emitter of the first transistor is grounded; the base of the first transistor is configured for receiving the switch signal; the base of the second transistor is connected to the collector of the first transistor; the emitter of the second transistor is connected to the primary power source and configured for receiving power from the primary power source; the collector of the second transistor is configured for outputting power from the primary power source; the base of the third transistor is configured for receiving the switch signal; the emitter of the third transistor is configured for receiving power from the secondary power source; the collector of the third transistor is configured for outputting power from the secondary power source.