Patent ID: 8198875

Claim:
A voltage regulator, comprising: an output transistor that is provided between a power supply terminal and an output terminal; an error amplifier for controlling a gate voltage of the output transistor so that a voltage of the output terminal becomes constant; a second transistor for connecting a substrate of the output transistor with the power supply terminal; a third transistor for connecting the substrate of the output transistor with the output terminal; and a comparator circuit for comparing a voltage of the power supply terminal with the voltage of the output terminal, and performing control of switching the second transistor and the third transistor based on a result of the comparing, wherein: the comparator circuit comprises: a fourth transistor having a source connected with the power supply terminal, a gate connected with a drain, and the drain connected with a first constant current circuit; and a fifth transistor having a source connected with the output terminal, a gate connected with the gate of the fourth transistor, and a drain connected with a second constant current circuit; and the comparator circuit outputs the result of the comparing based on a voltage of a connection point between the fifth transistor and the second constant current circuit.