| 摘要 |
PROBLEM TO BE SOLVED: To provide a protection circuit having a simple circuit and protecting a secondary battery against an overcharge and an overcurrent. SOLUTION: A comparator A1 outputs a high level signal if a voltage from the secondary battery 6 exceeds a predetermined reference (an overcharge protection voltage) Ref1, turns on a transistor Q1, carries a current to a heater R1, turns off a bimetal switch SW1, and protects the secondary battery 6 against the overcharge. A counter C1 counts up each time the comparator A1 outputs the high level signal. When the count value exceeds a predetermined value, the high level signal is outputted, a transistor Q2 is turned on, a current is carried to a heater R2, and a thermal fuse F1 is turned off. COPYRIGHT: (C)2007,JPO&INPIT
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