Power switch circuit

A power switch circuit, comprising:

• a power switch, having an output terminal for providing an output voltage and an output current;
• a sensing circuit, coupled to the power switch, sensing the output current and outputting a current sensing signal;
• a selecting circuit, respectively coupled to the output terminal and the sensing circuit, controlling the sensing circuit according to the output voltage, so that the sensing circuit selectively outputs a first sensing signal or a second sensing signal as the current sensing signal;
• and
• a modulating circuit, coupled to the sensing circuit and a control terminal of the power switch, outputting a controlling voltage to the control terminal of the power switch, and modulating the controlling voltage according to the current sensing signal,
• wherein the sensing circuit comprises:
• a sensing node, coupled to the modulating circuit, outputting the current sensing signal;
• a first current sensing circuit, coupled between the power switch and the sensing node, generating the first sensing signal related to the output current;
• and
• a second current sensing circuit, coupled between the power switch and the sensing node, generating the second sensing signal related to the output current,
• wherein when the output voltage is higher than a preset value, the selecting circuit controls the sensing circuit to output the first sensing signal to the sensing node, when the output voltage is lower than the preset value, the selecting circuit controls the sensing circuit to output the second sensing signal to the sensing node,
• wherein during a switching period in which the sensing circuit selectively outputs the first sensing signal or the second sensing signal as the current sensing signal, the sensing circuit simultaneously outputs the first sensing signal and the second sensing signal to the sensing node.