Patent ID: 9722538
Date: 2017-08-01
CPC Classifications: H03B,H03L

Claim:
1. A constant voltage circuit configured to output a constant voltage for driving an oscillation device including a crystal oscillation circuit, the constant voltage circuit comprising: a reference voltage circuit configured to output a reference voltage using a mirror current of a constant current source; a differential amplifier circuit to which the reference voltage and a feedback voltage that is based on the constant voltage are input; an output transistor configured to output the constant voltage to an output terminal of the constant voltage circuit using an output voltage of the differential amplifier circuit; and a leakage current detection circuit, between an output terminal of the reference voltage circuit and a gate of the output transistor, and configured to detect a leakage current of a transistor based on the reference voltage, wherein, when the leakage current detection circuit detects that the leakage current exceeds a predetermined value, the leakage current detection circuit increases a gate-source voltage of the output transistor.