| 摘要 |
PURPOSE:To prevent the parts of a converter or a DC input power source from becoming defective by inserting a variable impedance circuit between the DC input side and a DC output side, and controlling the impedance circuit by the variation in the voltage drop occurred by a load current. CONSTITUTION:A variable impedance circuit Z having a transistor Q3, resistors R2, R3 and an overcurrent limiter are inserted between a DC input V1 side and the output V2 side of a DC/DC converter. A current flowed to a resistor R1 inserted in series with a return path of the load current is monitored by a voltage detector OP, when the voltage across the resistor R1 exceeds the prescribed level, the drive voltage of a transistor Q1 is suppressed through a transistor Q2, a resistor R4 and a diode D2, and the output of the converter is limited, and the impedance of the circuit Z is simultaneously increased through a diode D3 to limit the flow out of the output current from a DC input power source B. |
