Semiconductor integrated circuit device including a pad and first mosfet

A semiconductor integrated circuit device, comprising:

• a pad for an input or output signal;
• a first MOSFET connected between said pad and a power supply wiring of a potential V0, the first MOSFET comprising a gate terminal and backgate directly connected in common;
• and
• a potential control circuit that controls a potential Vb of the gate terminal and the backgate of said first MOSFET based on a potential Vin of said pad,
• wherein said potential control circuit controls so that, if said first MOSFET is an n-type, Vb=V0 when Vin≧V0+Vth (where Vth is a predetermined positive potential), and Vb=Vin when Vin<V0−Vth, and if said first MOSFET is a p-type, Vb=Vin when Vin≧V0+Vth, and Vb=V0 when Vin<V0−Vth.

A semiconductor integrated circuit device, comprising:

• a first node connected to a pad;
• a first MOSFET connected between the first node and a power supply, the first MOSFET comprising a gate and a backgate, the gate and backgate directly connected in common;
• and
• a potential control circuit connected between the first node, a second node provided the gate and backgate of the first MOSFET, and a third node provided between the power supply and the first MOSFET,
• wherein the potential control circuit is configured to control a potential of the gate and backgate of the first MOSFET based on a potential provided to the pad, the potential of the gate being equal to the potential of the pad when the potential of the pad is greater than a predetermined threshold potential and the potential of the gate being zero when the potential of the pad is less than or equal to the predetermined threshold potential and the potential of the gate.