| 摘要 |
PURPOSE:To prevent the breakdown of an internal circuit, by providing a resistor between an input pad part and an internal input circuit, forming a parasitic MOS between a guard ring which is provided at the periphery of a substrate and the pad, and conducting the MOS when a high potential is applied to the pad part. CONSTITUTION:A resistor R is provided between an internal input circuit 20 constituted by an MOSFET and a pad part P. A clamping MOSFETQ1 is conducted and clamped when an input potential to the circuit 20 becomes a higher potential than an ordinary signal level. An electrostatic-breakdown preventing parasitic MOSQ3 is formed between a guard ring 16, which is provided along the periphery of a substrate 10 and the pad part P. Both a drain D and a gate G of the MOSQ3 are connected to the pad part P. A source S is connected to the guard ring 16. When a high potential is applied to the pad part P, the MOSQ3 is conducted and the breakdown of the internal input circuit is prevented. |
