| 摘要 |
PROBLEM TO BE SOLVED: To provide a secondary battery protective circuit which can charge a secondary battery even if the residual voltage of the secondary battery to be charged is 0 V. SOLUTION: (1) When the residual voltage of a secondary battery is 0 V, the battery 1 is connected to terminals (1) and (2) (at that time, a clamping circuit is in an inactive state). (2) A transistor 10 is made to be electrically continuous by the voltage of a charger 2. (3) As a result, a current I2 is applied to a resistor 5 and a transistor 3 is made to be electrically continuous. When the transistor 3 is electrically continuous, a charging control circuit 9 is driven and the charging of the battery 1 is started. (4) In accordance with the progress of the charging, the clamping circuit 14 is activated and the potential of a point E is elevated to the ground potential or higher and the transistor 10 is cut off. (5) Even if the transistor 10 is cut off, the electrical continuity of the transistor 3 is maintained by the voltage of the charged battery 1 and driving signals are continuously applied to the charging control circuit 9.
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