Patent ID: 7889469

Claim:
An electrostatic discharge (ESD) protection circuit comprising: a first power supply potential terminal to which a first power supply potential is applied; a reference potential terminal to which a reference potential is applied; an input terminal provided between the first power supply potential terminal and the reference potential terminal; a discharge circuit which holds a potential difference between the first power supply potential terminal and the reference potential terminal at a predetermined value; a first p-type MOSFET having a gate connected to the input terminal; a first n-type MOSFET having a gate connected to the input terminal; a second n-type MOSFET connected between the first n-type MOSFET and the reference potential terminal, and having a gate to which a first control signal is supplied; and a detection circuit connected between the first power supply potential terminal and the reference potential terminal, the detection circuit outputting the first control signal which turns on the second n-type MOSFET while the potential difference between the first power supply potential terminal and the reference potential terminals is held at the predetermined value, and outputting the first control signal which turns off the second n-type MOSFET while the potential difference between the first power supply potential terminal and the reference potential terminal deviates from the predetermined value.