| 摘要 |
PROBLEM TO BE SOLVED: To detect the deterioration of a protector even if a constituent element of the protector is deteriorated when a large surge voltage or current comes from an external line and thereby protect an inside electronic apparatus. SOLUTION: This circuit 4 is provided with a fuse 5 connected between the output of a protector 3 and an internal line 2, a current detection part 6 that is connected to the output of the protector 3 and generates a deterioration signal of the protector 3 at the time of the detection of the deterioration, and a switch 7 connected between the output of the current detection part 6 and the output side to an electronic apparatus of the fuse 5. The current detection part 6 is composed of a resistor to branch the current flowing through the fuse 5, an amplifier to amplify a voltage produced between both the ends of the resistor, a rectifying circuit to rectify the output signal of the amplifier, and a comparator that compares the output of the rectifying circuit with a reference voltage and outputs the comparison result as a deterioration detection signal.
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