Power switch circuit having variable resistor coupled between input terminal and output transistor and changing its resistance based on state of output transistor

A power switch circuit, comprising:

• an output transistor connected between a power supply terminal and a load;
• a protection circuit which protects said output transistor;
• a resistance element that transmits a drive signal voltage of said output transistor, and that is provided by a first conductivity type region as a resistance component formed in a second conductivity region;
• and
• a switching circuit which supplies said second conductivity type region, with a potential which changes in accordance with said drive signal voltage when said protection circuit does not operate, and with a potential which brings said first conductivity type region into a pinch-off state when said protection circuit operates.

A semiconductor device, comprising:

• an output transistor coupled between a first power source terminal and an output terminal for driving a load;
• a protection circuit including:
• an abnormal detecting circuit, coupled between the first power source terminal and the output terminal, which outputs a control signal;
• and
• a first switch, coupled between a control gate of the output transistor and the output terminal, including a control gate thereof receiving the control signal;
• a diffusion region including a first node coupled to an input terminal and a second node coupled to the control gate of the output transistor, the diffusion region being formed in a well region;
• and
• a switching circuit including:
• a resistor coupled between the well region and the output terminal;
• and
• a second switch, coupled between the well region and a second power source terminal, including a control gate thereof receiving the control signal.