Patent ID: 7358709

Claim:
A constant voltage regulator, comprising: an input terminal to receive a third voltage; an output terminal to output a first voltage to an external host apparatus; an output transistor to output a current in accordance with a signal input to a control gate thereof; an output voltage controller to generate a reference voltage, to produce a feedback voltage in proportion to the first voltage, to amplify a difference voltage between the reference voltage and the feedback voltage, and to output a signal of the amplified difference voltage to the control gate of the output transistor; and a switching circuit to selectively output one of a second voltage greater than the first voltage and the third voltage greater than the second voltage to a substrate gate of the output transistor in response to an operation mode of the constant voltage regulator switchable between a first mode in which a current to be output to the external host apparatus is smaller than a predetermined value and a second mode in which the current to be output to the external host apparatus is greater than the predetermined value.