| 摘要 |
PROBLEM TO BE SOLVED: To prevent the breakdowns of semiconductor devices which are caused by a steeply varying electrostatic discharge (ESD). SOLUTION: In an electrostatic-discharge protection circuit, when a voltage extremely higher than VDD1 is applied to a power supply line 11 due to ESD, a high potential difference is generated in the portion interposed between VDD1 and VSS. At this time, a clamping circuit 13 forms a current path for making the charge caused by the excessive voltage flow into a grounding line 12. Consequently, a current flows into the GND of a circuit block 10 to prevent the high potential difference from being generated in the portion interposed between VDD1 and VSS. Further, at this time, the excessive voltage applied to a signal line 40 is suppressed from varying its level steeply by virtue of a protection circuit 14. As a result, the breakdowns of the gate oxide films of the transistors present on a reception side can be prevented. COPYRIGHT: (C)2008,JPO&INPIT
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