Battery protection circuit

• US 20060267557A1
• Filed: 01/30/2006
• Published: 11/30/2006
• Est. Priority Date: 05/31/2005
• Status: Active Grant

• Current Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Original Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Inventors: Nakano, Itsuki, Kimura, Daisuke, Ooshita, Kazuhiro
• Granted Patent: US 7,541,777 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

A battery protection circuit includes an abnormal condition detection circuit having a resistor through which a current flows from a load in response to a current flowing in the load. The resistor generates a voltage in response to the current flowing in the load. The battery protection circuit further includes a control circuit having a detection stop switch configured to control the current flowing in the resistor from the load. The control circuit turns off the detection stop switch and a protection switch connected between the battery and the load when the abnormal condition detection circuit detects the abnormal condition according to the voltage generated by the resistor. The control circuit returns the detection stop switch to an ON state after returning the protection switch to an ON state in response to a start of supplying power from the battery to the battery protection circuit.

Claims

1. A battery protection circuit comprising:

an abnormal condition detection circuit including a current detection resistor through which a current flows from a load in response to a current flowing in the load, said resistor generating a voltage in response to the current flowing in the load, said abnormal condition detection circuit being able to detect an abnormal condition of a battery according to the voltage generated by the resistor; and

a control circuit including a detection stop switch configured to control the current flowing in the resistor from the load, said control circuit being able to turn off the detection stop switch and a protection switch connected between the battery and the load when the abnormal condition detection circuit detects the abnormal condition;

wherein

said control circuit returns the detection stop switch to an ON state after returning the protection switch to an ON state in response to a start of supplying power from the battery to the battery protection circuit.

2. The battery protection circuit as claimed in claim 1, wherein

said control circuit includes a power-on-reset circuit able to output a reset signal in response to the start of supplying power from the battery to the battery protection circuit, and a latch circuit able to reset an output thereof in response to the reset signal-output from the power-on-reset circuit, said control circuit returning the protection switch to the ON state by the output of the latch circuit being reset.

3. The battery protection circuit as claimed in claim 1, wherein the abnormal condition detection circuit further includes:

an overcurrent detection circuit able to compare the voltage generated by the resistor with a first reference voltage and output an overcurrent signal when the voltage generated by the resistor is greater than the first reference voltage;

a delay circuit including a capacitor, said delay circuit being able to charge the capacitor when the overcurrent signal is supplied from the overcurrent detection circuit and output an abnormal signal when a charging voltage of the capacitor is greater than a second reference voltage; and

a short-circuit detection circuit able to compare the voltage generated by the resistor with a third reference voltage and output an abnormal signal when the voltage generated by the resistor is greater than the third reference voltage; and

wherein said control circuit further includes;

an output circuit able to turn off the protection switch when the abnormal signal is supplied from one of the delay circuit and the short-circuit detection circuit; and

a logic circuit able to turn off the detection stop switch after the protection switch is turned off by an output of the output circuit.

4. The battery protection circuit as claimed in claim 3, wherein the logic circuit monitoring a voltage of the battery returns the detection stop switch to the ON state in response to a start of supplying the voltage of the battery to the battery protection circuit.

5. The battery protection circuit as claimed in claim 1, further comprising a reset switch configured to control a voltage supplied from the battery to the control circuit.