Patent ID: 7791315
Filing Date: 2010-09-07
Classification: H02J

Abstract:
1. A battery state monitoring circuit, comprising: an over-charge detecting circuit that monitors a voltage between both ends of a battery to detect an over-charge state; an over-discharge detecting circuit that monitors a voltage between the both ends of the battery to detect an over-discharge state; an over-current detecting circuit that monitors a voltage at an over-current detection terminal to which a voltage between an external terminal and a switch circuit is input to detect an over-current state; a logic circuit that controls charge and discharge of the battery on the basis of a detection signal sent from any one of the over-charge detecting circuit, the over-discharge detecting circuit, and the over-current detecting circuit, and outputs a power-down signal to the over-charge detecting circuit, the over-discharge detecting circuit, and the over-current detecting circuit that powers down the over-charge detecting circuit, the over-discharge detecting circuit, and the over-current detecting circuit in the over-discharge state to the over-charge detecting circuit, the over-discharge detecting circuit, and the over-current detecting circuit; and a power-down preventing circuit that outputs a power-down prevention signal that prevents the over-charge detecting circuit, the over-discharge detecting circuit, and the over-current detecting circuit from being powered down to the logic circuit when a voltage at the over-current detection terminal is lower than a given voltage.