A switch control circuit includes a power switch, a first protection unit, and a second protection unit. The power switch has a first terminal coupled to a first voltage terminal for receiving a first voltage, a second terminal coupled to a second voltage terminal for receiving a second voltage, and a control terminal receives a control voltage. In a first mode, the control voltage is greater than the first voltage. In a second mode, when a voltage of the second voltage terminal is smaller than a first reference voltage, the first protection unit pulls down the control voltage to reduce a current flowing through the power switch. When the voltage of the second voltage terminal is smaller than the second reference voltage, the second protection unit pulls down the control voltage to a ground voltage.