Patent ID: 6034508
Filing Date: 2000-03-07
Classification: H02J

Abstract:
A power-source-switching device capable of extending the working life of a battery, wherein the power-source-switching device is used to direct power either from a battery or an external power source to an all-time circuit, the device comprising:a power-source detection circuit coupled to an external power source for detecting whether or not an external power is present, and then outputting a power-source detection signal; anda switching circuit having two input terminals and a load-supporting power output terminal such that the input terminals are respectively connected to the battery and the external power source and the output terminal is connected to the all-time circuit, wherein the switching circuit also has an input terminal for receiving the power-source detection signal from the power-source detection circuit so that when the external power source is applied, the external power source is directed to the load-supporting power output terminal of the switching circuit, and, on the other hand, when the external power source is absent, power from the battery is directed to the load-supporting power output terminal of the switching circuit.