| 摘要 |
PURPOSE: To provide a power source circuit wherein enlargement of chip area and increase of cost can be prevented, while normal operation is ensured when a voltage higher than or equal to an element withstand voltage is applied. CONSTITUTION: A transistor Tr1 outputs an inputted DC voltage VCH as an internal power source Vo. When the DC voltage VCH turns to an overvoltage, a clamp circuit 1 becomes active and clamps the internal power source Vo at a prescribed voltage. As the result of activation of the clamp circuit 1, a gate voltage control circuit 3 controls a gate voltage of the transistor Tr1 in such a manner that the overvoltage is reduced and supplied as the internal power source Vo.
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