| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-power supply protective circuit which attains a function equivalent to that of an electrostatic protective device used in a semiconductor integrated circuit where a multi-power supply is present, protects a semiconductor device against damage independently of the power closing order of a multi-power supply, and realize the reduction of the device in size. SOLUTION: A multi-power supply protective circuit is equipped with a voltage monitoring switching circuit 4 which monitors the voltage of a power supply and turns a switching device on or off corresponding to a monitoring result, an electrostatic protective device 1 which is connected to a first power supply pattern from the output terminal of the voltage monitoring switching circuit 4, an electrostatic protective device 2 which is connected to a second power supply pattern from a grounding pattern, and an electrostatic protective device 3 which is connected to the first power supply pattern from the grounding pattern. The first and second power supply terminal of the voltage monitoring switching circuit 4 are each connected to the first and second power supply pattern, the grounding terminal 8 of the voltage monitoring switching circuit 4 is connected and grounded to the grounding pattern, the switching device and the protective device 1 are connected between the second power supply pattern and the first power supply pattern, and the switching device is turned off to shut off a path until a high potential voltage reaches a required potential higher than a low potential voltage.
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