| 摘要 |
PROBLEM TO BE SOLVED: To provide a power source circuit capable of reducing the current capabilities of an input side DC power source, and preventing the generation of any failure such as hit due to rush currents. SOLUTION: A DC power source is supplied from an output terminal (16) through an output transistor (Q1) to a load, and the driving of the output transistor (Q1) is controlled so that the voltage of the output terminal (16) can be made constant according to an error voltage obtained by comparing the voltage of the output terminal (16) with a reference voltage. This power source circuit is provided with a current detecting circuit (Q2) for detecting currents flowing through the output transistor (Q1) and a soft start circuit (20) for suppressing the driving of the output transistor (Q1) according to the currents detected by the current detecting circuit (Q2) at the time of start. Thus, it is possible to suppress rush currents at the time of start, and to prevent the generation of hit due to the rush currents even when the current capabilities of the input side DC power source are small.
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