Patent ID: 7965287

Claim:
A power supply switching circuit, comprising: a first input configured to receive a first signal; a second input configured to receive a second signal; a first voltage regulating circuit comprising a plurality of first semiconductor elements electrically coupled in series; and a signal switching circuit configured for switching between the first and second signals, the signal switching circuit comprising a first input terminal, a second input terminal, and an output terminal; wherein the first input is electrically coupled to the first input terminal of the signal switching circuit via the first voltage regulating circuit, the second input is electrically coupled to the second input terminal of the signal switching circuit, the output terminal of the signal switching circuit is configured to be an output of the power supply switching circuit, and the first voltage regulating circuit is configured to regulate the first signal according to voltage drops of the first semiconductor elements; wherein the signal switching circuit further comprises a first transistor and a second transistor, an emitter electrode and a collector electrode of the first transistor are respectively configured to be the first input terminal and the output terminal, a base electrode of the first transistor is directly grounded through a resistor and directly electrically coupled to an emitter electrode of the second transistor through a resistor, the emitter electrode of the second transistor is configured to be the second input terminal, a base electrode of the second transistor is directly grounded through a resistor, and the collector electrode of the second transistor is electrically coupled to the output terminal.