Patent ID: 7847530

Claim:
A voltage regulator converting an input voltage input to an input terminal into a predetermined constant voltage, and outputting the converted voltage from a predetermined output terminal as an output voltage, the voltage regulator comprising: a first output transistor configured to output a first current according to an input first control signal from the input terminal to the output terminal; a second output transistor configured to output a second current according to an input second control signal from the input terminal to the output terminal; and a control circuit part configured to control operations of the first output transistor and the second output transistor so that a voltage proportional to the output voltage output from the output terminal is equalized with a predetermined reference voltage, the control circuit part including a first error amplifier circuit configured to amplify and output a difference between the proportional voltage and the reference voltage and a second error amplifier circuit configured to amplify and output the difference between the proportional voltage and the reference voltage, the second error amplifier circuit being configured to consume a smaller amount of current than the first error amplifier circuit, wherein the control circuit part is configured to control the output voltage by performing, in accordance with an externally input external control signal, one of controlling the operations of the first output transistor and the second output transistor using the first error amplifier circuit and controlling the operation of the second output transistor using the second error amplifier circuit.