Semiconductor integrated circuit

Abstract

A semiconductor integrated circuit with an input protection circuit, a switch element that is switched according to a voltage applied to both terminals is provided between a wiring for connecting an input terminal and the input point of an input initial stage inverter and the output point of either logic gate for constituting an internal circuit. When an overvoltage is applied to the external input terminal, the switch device becomes the conducting condition so that the electric charge of the overvoltage applied to the external input terminal, is discharged through a MOS transistor constituting the logic gate within the internal circuit, to a power supply voltage line or a ground potential line which is laid within the internal circuit for supplying a power supply voltage or a ground potential transistor.

Description

Technical field [0001] The present invention relates to a semiconductor integrated circuit, and more particularly, to a semiconductor integrated circuit having an input protection circuit capable of discharging a surge voltage such as an electrostatic overvoltage applied to an external terminal at a power supply potential point or a ground potential point. Background technique [0002] Use 5, 6, or 7 to describe this type of input protection circuit previously used for input protection of a semiconductor integrated circuit (LSI). Figure 5 It is a circuit diagram of one of the previous input protection circuit examples (existing example 1). Refer to Figure 5 , On the power supply voltage side, a P-channel MOS transistor (PMOS transistor) Q is provided as a protection element for discharging current p3 . Transistor Q p3 A diode is used to connect the gate and the source, the gate and the source are connected to the power supply voltage line 1, and the drain is connected to the ex...

AI Technical Summary

Problems solved by technology

The result is a large input protection circuit, which in turn increases chip area

[0008] The second problem is that as mentioned above, as the area of ​​the input protection circuit increases, the diffusion layer capacitance and gate capacitance of the input protection element increase, and the input terminal capacitance also increases.

[0009] The third problem is that because the resistance on the discharge path of the input protection circuit is particularly small, it is convenient for current to flow, and the design of the circuit increases the restriction that the input protection circuit must be configured near the power supply voltage line and the ground line.

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