| 摘要 |
PURPOSE:To enable an operation to be performed by a source voltage at a load side extending over a wide range by energizing an inter-input/output short- circuiting circuit at the time of detecting the fact that the input voltage of a power source stabilization circuit is less than a prescribed voltage by a low voltage detection circuit. CONSTITUTION:The power source stabilization circuit 15 that is the constituent of an output circuit is provided with the low voltage detection circuit 21 and the inter-input/output short-circuiting circuit 22 in addition to a series dropper type stabilization circuit 23. The low voltage detection circuit 21 includes transistors TR1 and TR2, a Zenor diode Z2, and resistors R1, R2, R3, and R4, and the inter-input/output short-circuiting circuit 22 is provided with a transistor TR3 as a short-circuiting switching device. And in a range where the input voltage Vi is less than the Zenor voltage Vz2 of the Zenor diode Z2, the low voltage detection circuit 21 short-circuits the inter-input/output short-circuiting circuit 22. In such a way, it is possible to guarantee the gate voltage of an output transistor even when the worst condition in voltage fluctuation a component constant, etc., is generated.
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