Patent Number: 6,885,168

Title: Battery unit having means for preventing over-discharge

Abstract: A protection method for preventing battery cells from over-discharging and being overcharged, a control circuit, and a battery unit are provided. In the protection method, when a set signal "1" is supplied to a set terminal, a flip-flop outputs "1". The gate of a discharge control FET then becomes "1", so that the discharge control FET is OFF regardless of a discharge control signal supplied from a voltage monitor circuit. When a reset signal "1" is supplied to a reset terminal, the flip-flop outputs "0". The discharge control FET is then switched on and off in accordance with the output of a discharge control circuit of the voltage monitor circuit. In this manner, battery cells connected to an electronic device do not over-discharge, even when they are left unused for a long period of time. Thus, the battery unit can be prevented from deteriorating and shortening the life thereof.

Inventors: Okumura; Masafumi (Kawasaki, JP), Tanaka; Shigeo (Kawasaki, JP)

Assignee: Fujitsu Limited

International Classification: H02H 7/18 (20060101); H02J 7/00 (20060101); H01M 10/42 (20060101); H02J 007/00 ()

Expiration Date: 04/26/2022