Frishauf, Holtz, Goodman, Langer & Chick
Overcharge and overdischarge protection for a chargeable electric cell operable with a reduced current consumption
 A protection circuit for an electric cell comprises an overcharge detection circuit (43-1, 43-2) and an overdischarge detection circuit (44-1, 44-2) both of which are connected to a chargeable electric cell (41, 42) to detect an overcharged condition and an overdischarged condition of the electric cell (41, 42), respectively. A switch (S11, S12) is inserted in a power supply line of the chargeable electric cell (41, 42) and is turned off, when the overcharge detection circuit (43-1, 43-2) or the overdischarge detection circuit (44-1, 44-2) detects the overcharged or the overdischarged condition, thereby inhibiting a charging or a discharging operation. At least the overcharge detection circuit (43-1, 43-2) of the above-mentioned two detection circuits (43-1, 43-2, 44-1, 44-2) is connected to a timing signal producing circuit (45) for supplying a first timing signal having a first duration t1 for defining an operation timing thereof, and to a processing circuit (46) for processing an output signal of the overcharge detection circuit (43-1, 43-2) activated by the first timing signal to judge the presence or absence of an overcharged condition and for turning off the switch (S11) upon Judgement of the presence of the overcharged condition. 
Mitsumi Electric Co., Ltd.
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inventional inventional inventional
Masaru Yasuhisa
Takeuchi Higashijima