Battery protection ic and battery device
AssigneeSeiko Instruments Inc.
InventorsYoshihisa Tange, Atsushi Sakurai, Takakazu Ozawa, Kiyoshi Yoshikawa
Life of this patent
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Abstract
Provided are a battery protection IC adaptable to any number of batteries connected in series without increasing a breakdown voltage thereof, and a battery device including the battery protection IC mounted thereon. A charge control signal input terminal and a discharge control signal input terminal of one battery protection IC are provided with a clamp circuit (121), and hence an output driver (112) of another battery protection IC connected to those terminals is not applied with a voltage equal to or higher than a breakdown voltage. Accordingly, the breakdown voltage of the battery protection IC is not required to be high.
Claims6
A battery protection IC for protecting a battery, comprising:
- a charge control signal output terminal for outputting a charge control signal which controls charging from a charger to the battery;
- a voltage monitoring circuit for monitoring a battery voltage of the battery, and detecting, when the battery voltage becomes equal to or higher than an overcharge detection voltage, that the battery voltage becomes equal to or higher than the overcharge detection voltage to output a detection signal;
- an output driver of a first conductivity type for being turned off to cut off a charge current when the detection signal is output;
- a charge control signal input terminal for receiving input of the charge control signal, the charge control signal input terminal being connected with a resistor in an outside thereof;
- a transistor of the first conductivity type for being turned off when a voltage of the charge control signal input terminal is pulled to a source voltage side by a voltage generated in the resistor, and being turned on when the charge control signal input terminal is opened or HIGH is input to the charge control signal input terminal;
- and
- a clamp circuit for clamping a gate voltage of the transistor to a predetermined voltage,
- the output driver being turned on when the transistor is turned off, and being turned off when the transistor is turned on to cut off the charge current.
A battery device, comprising:
- a plurality of battery protection ICs for protecting a battery mounted thereon, each including:
- a charge control signal output terminal for outputting a charge control signal which controls charging from a charger to the battery;
- a voltage monitoring circuit for monitoring a battery voltage of the battery, and detecting, when the battery voltage becomes equal to or higher than an overcharge detection voltage, that the battery voltage becomes equal to or higher than the overcharge detection voltage to output a detection signal;
- an output driver of a first conductivity type for being turned off to cut off a charge current when the detection signal is output;
- a charge control signal input terminal for receiving input of the charge control signal;
- a transistor of the first conductivity type for being turned off when a voltage of the charge control signal input terminal is pulled to a source voltage side, and being turned on when the charge control signal input terminal is opened or HIGH is input to the charge control signal input terminal;
- and
- a clamp circuit for clamping a gate voltage of the transistor to a predetermined voltage,
- the output driver being turned on when the transistor is turned off, and being turned off when the transistor is turned on to cut off the charge current;
- a plurality of the batteries each provided in parallel with each of the plurality of battery protection ICs;
- one or more resistors each provided between the charge control signal input terminal of the battery protection IC of an upper stage and the charge control signal output terminal of the another battery protection IC, the another battery protection IC being provided at a preceding stage of the battery protection IC of the upper stage;
- and
- a charge control transistor of a second conductivity type which includes a gate provided at the charge control signal output terminal of the battery protection IC of an uppermost stage, is provided in a charge path, and is turned off to cut off the charge current when the detection signal is output, for controlling charging.
Dependencies are inferred from the claim text.