PROTECTIVE CIRCUIT OF SECONDARY BATTERY

Japanese Patent JPH09233713

A

PROBLEM TO BE SOLVED: To inform used equipment such as a charger or a batter of its abnormality and prevent overcharge or overdischarge by changing the temperature detection output into the signal equivalent abnormal temperature, when this protective circuit detects the abnormality of the charge condition or discharge condition of a secondary battery. SOLUTION: Secondary batteries 1 and 2 are charged by fixed voltage charge method used for, for example, a lithium secondary battery, a lead battery, etc. The batteries 1 and 2 are connected in series, and n-channel FETs 3 and 4 constituting first and second switch elements are connected in series to the charge/discharge circuit. The parasitic diodes D1 and D2 of the FETs 3 and 4 get in forward direction at the time of charge and discharge. In a protective circuit, the + terminal, to the + terminal of the battery 1, and the - terminal, to the source of the FET 3, and a thermistor 1, between the outer terminal T and the - terminal, are connected. The thermistor 11 operates overcharge or overdischarge preventive circuits 5 or 6 through a transistor 12 and an abnormality detection circuit 10 so as to charge or discharge it properly when the temperature during charge or discharge deviates from the specified range.

MITO TOSHITSUGU
KIZAWA MASAHITO
NAKAGAWA HIROSHI
MUKAI KAZUO
SHIOJIMA NOBUO
ISSHIKI MASANORI
ITO NORIYUKI

JP3219196A

September 05, 1997

February 20, 1996

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IBM
A T BATTERY KK
TOSHIBA BATTERY

G01R31/36; H01M10/44; H01M10/48; H02H7/18; H02J7/00; (IPC1-7): H02J7/00; G01R31/36; H01M10/44; H01M10/48; H02H7/18

Takehiko Suzue

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