A control circuit for controlling a power supply is revealed. The control circuit is used to generate a switching signal for switching the power supply. The control circuit has a detection terminal for detecting a status of the power supply. A first protection circuit is coupled to the detection terminal and to receive a first detection signal via the detection terminal, and the first protection generates a limit signal in response to the first detection signal, for limiting output of the power supply. A second protection circuit is coupled to the detection terminal and to receive a detection signal via thereto, and the second protection generates a protecting signal, for cutting off the output of the power supply, in response to the first detection signal. A phase dividing circuit is coupled to the detection terminal, the first protection circuit and the second protection circuit, and to generate the first and second detection signal in response to the level of the switching signal, for achieving that two independently adjusted protection circuit are detected by one pin of an integrated circuit (IC) to prevent the IC from increasing of the pin amount. It further reduces the occupied area of the IC.