Seiko Instruments Inc

Shohei Tsukamoto

Atsushi Sakurai

Kazuaki Sano

Toshiyuki Koike

Fumihiko Maetani

Wataru Sakamoto

Provided is a battery state monitoring circuit which detects that a voltage of a secondary battery has decreased abruptly because of an overcurrent, thereby being capable of protecting a battery device from an abrupt decrease in voltage of the secondary battery caused by the overcurrent. The battery state monitoring circuit includes a voltage comparator circuit and a power supply voltage detection circuit for detecting an abrupt decrease in power supply voltage, in which the voltage comparator circuit detects a normal overcurrent while the power supply voltage detection circuit detects the abrupt decrease in power supply voltage caused by load short-circuit.

Battery state monitoring circuit and battery device

Provided are a battery state monitoring circuit with a small number of terminals and a battery device including the battery state monitoring circuit. An output of an overcharge detection circuit () is an open-drain output to a charge control terminal (), and an input terminal of a voltage detection circuit () is connected to the charge control terminal (), to thereby share a charger detection terminal and a charge control terminal.

Provided are a battery state monitoring circuit capable of detecting disconnection of a battery from a power supply terminal or a ground terminal, and a battery device including the battery state monitoring circuit. The battery state monitoring circuit includes voltage detection circuits provided between the power supply terminal and an intermediate terminal and between the intermediate terminal and another intermediate terminal. For example, if a battery () is disconnected from a power supply terminal (), the power supply terminal () is pulled down by a constant current circuit () to a voltage of a second intermediate terminal () so that a voltage detection circuit () detects the disconnection.

Provided are a battery state monitoring circuit and a battery device that are capable of reliably controlling charge by a charger even if a voltage of a secondary battery drops to around 0 V. In the battery device provided with the battery state monitoring circuit, respective gate voltages of a P-type metal oxide semiconductor (PMOS) transistor and an N-type metal oxide semiconductor (NMOS) transistor, which together form a voltage detection circuit for detecting a voltage of around 0 V of the secondary battery, are applied by a voltage dividing resistor circuit that is connected across terminals of the secondary battery.

Growing community of inventors

Chiba, Japan

Shohei Tsukamoto