Patent ID: 8242637

Claim:
A power source switching circuit, comprising: a main source input terminal configured to be connected to a main source terminal of a power supply; an auxiliary source input terminal configured to be connected to an auxiliary source terminal of the power supply; a control circuit, the control circuit comprising a first comparator and a second comparator; the first comparator comprising a first positive input terminal, a first negative input terminal, and a first output terminal; the second comparator comprising a second positive input terminal, a second negative input terminal, and a second output terminal; the first positive input terminal connected to the auxiliary source input terminal; the first negative input terminal connected to the main source input terminal; the first output terminal connected to the second negative input terminal; the second positive terminal directly connected to the first positive terminal; a first switch, the first switch comprising a first switch control terminal, a first switch second terminal, and a first switch third terminal; the first switch control terminal connected to the first output terminal; and the first switch second terminal connected to the main source input terminal; a second switch, the second switch comprising a second switch control terminal, a second switch second terminal, and a second switch third terminal; the second switch control terminal connected to the second output terminal; and the second switch second terminal connected to the auxiliary source input terminal; and an output terminal connected to the first switch third terminal and the second switch third terminal.