OVERDISCHARGE PREVENTION CIRCUIT OF SECONDARY BATTERY AND SECONDARY BATTERY MODULE

Rapid degradation an off-leakage current in an overdischarged state is prevented. In order to prevent an overdischarged state, a control circuit with low leakage current includes a transistor using an oxide semiconductor, whereby the characteristics of the secondary battery are retained. In addition, a system in which a control signal generation circuit is also integrated is formed. With this system structure, the control circuit enters a low-power consumption mode in accordance with the circuit operation after an overdischarge is detected. When recovering from an overdischarged state, the control circuit enters a normally-operating mode in accordance with the voltage increase when charging is started.