A power delivery integrated circuit is installed within a cable, and a switch circuit applied to the power delivery integrated circuit includes a first switch module, a second switch module, and a logic controller. When a first terminal of the cable receives a first voltage and a second terminal of the cable receives a second voltage, the logic controller optionally makes the first switch module transmit the first voltage to an identification circuit of the power delivery integrated circuit, or makes the second switch module transmit the second voltage to the identification circuit.