Duplicate supply selection circuit

The invention provides a duplicate supply selection circuit, relates to the field of analog integrated circuits and aims at solving the technical problem of selecting a power source with high voltage value for power supply in the situation that two power sources are connected simultaneously. The duplicate supply selection circuit includes a bias circuit, a duplicate supply voltage comparison circuit and a power selection circuit; the input of the bias circuit is a first supply voltage and a second supply voltage, and the output is a bias voltage; the input of the duplicate supply voltage comparison circuit is the first supply voltage, the second supply voltage and the bias voltage, and the output is a comparison signal; and the input of the power selection circuit is the first supply voltage, the second supply voltage and the comparison signal, and the output is a selection voltage that is a supply voltage with a higher voltage value of the first supply voltage and the second supply voltage. The selection circuit can be applied in the circuit of a lithium ion battery charger.