| 摘要 |
PROBLEM TO BE SOLVED: To provide a current detection circuit capable of reducing a stand-by loss at a non-detection time of a current flowing in an external load. SOLUTION: This circuit is equipped with a direct current power source having an output voltage exceeding a rated voltage of a differential amplifier, and a series circuit comprising the differential amplifier 8 connected between the direct current power source and the ground, a current restriction resistance 11 and a switch circuit 13 to be opened at a sleep time. The differential amplifier 8 compares a voltage drop caused by a current flowing in a reference resistance 1 in an external load circuit comprising the reference resistance 1 and an external load 2 connected between the direct current power source and the ground with a voltage drop caused by a current flowing in a first comparing resistance 3 in a comparator comprising first and second comparing resistances 3, 5 connected between the direct current power source and the ground and a collector electrode and an emitter electrode of a comparing transistor 4. A base electrode of the comparing transistor 4 is controlled following the comparison result, and a current flowing in the external load 2 is detected based on the current flowing in the second comparing resistance 5, and the switch circuit 13 is opened at the sleep time when the current flowing in the external load 2 is not detected. COPYRIGHT: (C)2004,JPO&NCIPI
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