Patent ID: 8934204
Filing Date: 2015-01-13
Classification: H03K

Abstract:
1. A protection circuit for protecting a semiconductor integrated circuit against surges, comprising: a surge detecting circuit for detecting a surge applied to the semiconductor integrated circuit; a protecting element comprising a first MOS transistor of a first polarity for absorbing the surge, wherein said protecting element is connected between a signal terminal for supplying a signal to the semiconductor integrated circuit and a power source terminal for supplying a power source voltage, and wherein wherein a drain of the first MOS transistor is connected to the signal terminal and a source of the first MOS transistor is connected to the power source terminal, and the gate and the back gate of the first MOS transistor are commonly connected, and wherein said protecting element further comprises a second resistor connected between said power source terminal and said source of said second MOS transistor in said surge detecting circuit.