| 摘要 |
PURPOSE:To completely cut off an output transistor by monitoring a base current in a device which detects the abnormality of a circuit with a flowing current. CONSTITUTION:When a load 2 is short-circuited, the collector current which flows in the output transistor 3 rapidly increases. According to its, the base current of the output transistor 3 exceeds a frame which is absorbed by a Zenor diode 10 and remarkably increases in substance within a normal action range. Therefore, the condition that the base current flows in the base of a transistor 9 for selecting short-circuit through a diode 8 since the electric potential of both ends of a resistance 6 increases can be obtained. As a result, if the transistor 9 is turned on, the output transistor 3 is forcedly short-circuited between the base-emitter by the collector-emitter line of the transistor 9 for selecting short-circuit so as to be completely cut off.
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