| 摘要 |
PROBLEM TO BE SOLVED: To provide a current limiting circuit whose application conditions are not limited by the largeness of the difference between input and output voltages, and whose safety is improved. SOLUTION: A second driving transistor Q4 is provided to drive a switching transistor Q1 in accordance with signals from a controlling circuit 3, and a first resistor R5 is connected to the collector of the driving transistor Q4 and to a controlling transistor Q2 parallel to its collector-emitter. Then, a second resistor R6 is connected between the base of the controlling transistor Q2 and the collector of switching transistor Q1. Furthermore, a capacitor C4 is connected between the base and emitter of the controlling transistor Q2. A current limiting circuit 4a is made up of the driving transistor Q4, the resistors R5, R6, the controlling transistor Q2, and the capacitor C4.
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