Battery protecting apparatus and battery protecting circuit

• US 7,598,708 B2
• Filed: 08/30/2006
• Issued: 10/06/2009
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Original Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Inventors: Terada, Yukihiro, Kimura, Daisuke
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): Muralidar; Richard V
• Application Number:
  US11/512,690
• Publication Number:
  US 20070096695A1
• Time in Patent Office: 1,133 Days
• Field of Search: 320/134, 320/136, 320/132, 361/89, 307/10.7
• US Class Current: 320/132
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

A battery protecting circuit is disclosed that includes a negative voltage terminal voltage detecting circuit that detects when a voltage of a negative voltage terminal decreases to less than a predetermined voltage; an abnormality detecting circuit that detects an abnormality in charge/discharge conditions of a battery; a switch that is connected between the battery and the negative voltage terminal, the switch being turned off when the negative voltage terminal voltage detecting circuit detects that the voltage of the negative voltage terminal has decreased to less than the predetermined voltage and when the abnormality detecting circuit detects the abnormality in the charge/discharge conditions of the battery; a delay time reducing circuit that reduces a time period from a time the abnormality in the charge/discharge conditions of the battery is detected to a time the switch is turned off when the voltage of the negative voltage terminal decreases to less than the predetermined voltage; and an output invalidating circuit that invalidates an output of the negative voltage terminal voltage detecting circuit.

Claims

1. A battery protecting circuit, comprising:

a negative voltage terminal voltage detecting circuit that detects when a voltage of a negative voltage terminal decreases to less than a predetermined voltage;

an abnormality detecting circuit that detects an abnormality in charge/discharge conditions of a battery;

a switch that is connected between the battery and the negative voltage terminal, the switch being turned off when the negative voltage terminal voltage detecting circuit detects that the voltage of the negative voltage terminal has decreased to less than the predetermined voltage and when the abnormality detecting circuit detects the abnormality in the charge/discharge conditions of the battery;

a delay time reducing circuit that reduces a time period from a time the abnormality in the charge/discharge conditions of the battery is detected to a time the switch is turned off when the voltage of the negative voltage terminal decreases to less than the predetermined voltage; and

an output invalidating circuit that invalidates an output of the negative voltage terminal voltage detecting circuit during inspection, and that validates the output of the negative voltage terminal detecting circuit after the inspection,

wherein the negative voltage terminal voltage detecting circuit includes a comparator, and the output invalidating circuit is connected between an output of the comparator and ground without intervention of a switch.

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

the output invalidating circuit is connected between ground and the output of the negative voltage terminal voltage detecting circuit, and includes a fuse;

and

the output of the negative voltage terminal voltage detecting circuit is validated by melting the fuse.

3. The battery protecting circuit as claimed in claim 1, wherein

the negative voltage terminal voltage detecting circuit, the abnormality detecting circuit, and the output invalidating circuit are integrated in a single-chip.

4. The battery protecting circuit as claimed in claim 1, wherein the output invalidating circuit comprises a fuse.

5. The battery protecting circuit as claimed in claim 1, wherein the inspection is a period in which the operation of the abnormality detecting circuit is tested.