Patent ID: 7113378

Claim:
An electrostatic breakdown preventing protection circuit that prevents an electrostatic breakdown of a circuit to be protected, wherein the electrostatic breakdown preventing protection circuit comprises: an input terminal through which an external circuit is connected to the circuit to be protected, a first power supply terminal, a first MOSFET having a drain electrode that is connected to the input terminal and the circuit to be protected, and having a source electrode and a substrate or well electrode that are connected to the first power supply terminal, and a voltage control circuit that is connected to bridge the drain electrode and the source electrode of the first MOSFET, which controls a voltage of the gate electrode of the first MOSFET to prevent an electrostatic breakdown of the first MOSFET; wherein the voltage control circuit comprises a first protection element, the first protection element comprising an FET of the same conduction polarity as the first MOSFET, wherein a drain electrode of the first protection element is connected to the drain electrode of the first MOSFET, and a source electrode, gate electrode, and substrate electrode of the first protection element are connected to the gate electrode of the first MOSFET.