Battery charge control circuit
AssigneesSony Corporation, Nippon Motorola Ltd.
InventorsYasuhito Eguchi, Kanji Murano, Akira Sanpei, Hajime Tamiya
Life of this patent
Estimating the term…
Abstract
Circuit groups for preventing a battery from being deteriorated in efficiency due to a charging and discharging of each of secondary batteries is incorporated in a battery protection circuit for protecting a plurality of batteries connected in series to thereby extend a life of the battery. The battery protection circuit incorporates therein power down means for extending a time in which a voltage of a remaining capacity becomes 0V as much as possible by causing a current to flow only in the minimum circuit when the battery is overdischarged. Also, when a trouble such as a momentary overcurrent or the like is detected, the circuit can be prevented from set in the power down mode.
Claims7
A battery protection circuit comprising:
- a) a secondary battery;
- b) state detecting means for detecting a voltage of said secondary battery and detecting an overdischarged or overcharged state of said secondary battery by comparing said detected voltage with a reference voltage;
- c) first switching means for interrupting a discharging current;
- d) second switching means for interrupting a charging current;
- e) control means for controlling the switching of said first and second switching means on the basis of a detected result of said state detecting means;
- f) power down switching means for interrupting a supply voltage and the reference voltage supplied to said state detecting means;
- g) power down means for making said power down switching means enter a nonconductive state when the overdischarged state of said secondary battery is detected by said state detecting means;
- h) power down releasing means for returning said power down switching means from the nonconductive state to a conductive state when a charging of said secondary battery is started again from the overdischarged state;
- and
- i) state holding means for detecting that said secondary battery is started to be charged again from the overdischarged state by detecting the occurrence of a charging voltage produced across terminals of said secondary battery and for holding the detected charging state.
Dependencies are inferred from the claim text.