A switch circuit includes a voltage follower module, a comparison module and a switch module coupled to the voltage follower module, the comparison module and a power supply. The voltage follower can receive a first control signal and a second control signal. The comparison module can receive the first control signal and the second control signal. The comparison module compares a voltage of the first control signal and the second control signal with a reference voltage. When the comparison module outputs a first signal to turn on the switch module, the first power supply unit and the second power supply unit work in the first operation mode. When the comparison module outputs a second signal to turn off the switch module, the first power supply unit and the second power supply unit work in the second operation mode.