Battery state monitoring circuit and battery device
View Patent ↗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.
1. A battery state monitoring circuit for controlling charge and discharge of a secondary battery,
the battery state monitoring circuit comprising:
a charge/discharge control circuit that is connected across terminals of the secondary battery, for monitoring a voltage of the secondary battery;
a charge switch; and
a charge switch control circuit for outputting an output signal of the charge/discharge control circuit to the charge switch,
wherein the charge switch control circuit operates with a voltage between external terminals of the battery state monitoring circuit, and
wherein the charge switch control circuit comprises:
a level shifter circuit for converting the output signal of the charge/discharge control circuit into the voltage between the external terminals;
a voltage dividing resistor circuit that is connected across the terminals of the secondary battery, for generating a divided voltage;
a voltage detection circuit that is supplied with the divided voltage, for detecting a voltage for 0 V charge; and
an output circuit that is supplied with respective output voltages of the level shifter circuit and the voltage detection circuit, for controlling the charge switch.
2. A battery device, comprising:
a chargeable/dischargeable secondary battery;
a switch circuit that is provided between the chargeable/dischargeable secondary battery and an external terminal of the battery device, for controlling charge and discharge of the chargeable/dischargeable secondary battery; and
the battery state monitoring circuit according to claim 1 for monitoring a voltage across terminals of the chargeable/dischargeable secondary battery.