| 摘要 |
PROBLEM TO BE SOLVED: To provide a battery protecting device having high reliability and long cycle life. SOLUTION: When a battery voltage E1 is not more than a charge inhibiting voltage and not less than a discharge inhibiting voltage, a control circuit 8 controls a first and a second FET 6, 7, connected serially to a charge and discharge circuit in an on state. When the battery voltage E1 is not less than the charge inhibiting voltage, the control circuit 8 controls the first FET 6 to off-state, and when the terminal voltage E2 is lower than E1, the control circuit 8 controls the first FET 6 to on-state. When the battery voltage E1 is not more than the discharge inhibiting voltage, the control circuit 8 controls the second FET 7 to off-state, and when the terminal voltage E2 is lower than E1, the control circuit 8 controls the FET 7 to on-state. By this control, no current is caused to flow in parasitic diodes 6a, 7a of the first and the second FET 6, 7, and the deterioration due to generation of heat is prevented. Furthermore, when the voltage difference between unit batteries divided by the detection of an intermediate voltage E3 becomes a prescribed value or higher, the second FET 7 is controlled to off-state and stops discharging.
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