Patent ID: 7646574

Claim:
A voltage regulator, comprising: an error amplifier circuit that amplifies and outputs a difference between a divided voltage obtained by dividing a voltage which is output by an output transistor and a reference voltage to control a gate of the output transistor; and an overcurrent protective circuit which detects that an overcurrent flows in the output transistor to limit the current in the output transistor, wherein the overcurrent protective circuit comprises: an output current detection transistor that is controlled by an output voltage of the error amplifier circuit, and allows a detection current to flow therein; a detection resistor that generates a detection voltage by the detection current; an output current limiter circuit that is controlled by the voltage of the detection resistor, and controls the gate voltage of the output transistor; and a regulated cascode circuit that is connected between the drain of the output transistor and the drain of the output current detection transistor, and makes a voltage at the drain of the output transistor equal to a voltage at the drain of the output current detection transistor.