Patent ID: RE41915

Claim:
A charge/discharge control circuit for controlling charging and discharging of a secondary battery, wherein the secondary battery includes a cell, the control circuit comprising: an overdischarge detection circuit for comparing a voltage of the cell with a predetermined discharge reference voltage, determining whether the secondary battery is in an overdischarged state, and generating an overdischarge determination signal; an overcharge detection circuit for comparing the voltage of the cell with a predetermined charge reference voltage, determining whether the secondary battery is in an overcharged state, and generating an overcharge determination signal; a discharge control switch connected to the overdischarge detection circuit and deactivated in the overdischarged state based on the overdischarge determination signal; a first charge control switch deactivated in the overdischarged state based on the overdischarge determination signal and the overcharge determination signal; a second charge control switch activated in the overdischarged state based on the overdischarge determination signal and the overcharge determination signal; and a current-limiting circuit connected in series with the second charge control switch for limiting a charging current when charging is performed.