VOLTAGE DETECTION CIRCUIT

• US 20090237085A1
• Filed: 03/11/2009
• Published: 09/24/2009
• Est. Priority Date: 03/19/2008
• Status: Abandoned Application

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Suto, Daisuke
• Application Number:
  US12/402,068
• Publication Number:
  US 20090237085A1
• Time in Patent Office: Days
• US Class Current: 324/426
• CPC Class Codes: G01R 15/205 using magneto-resistance devices, e.g. field plates
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36

Abstract

A voltage detection circuit 1A comprises a coil 5 connected between positive and negative terminals of a battery 3 through input terminals T1 and T2, and an MR device R_M magnetically coupled to the coil 5. Employing such a structure makes it possible to detect the voltage of the battery 3 in real time according to a change of magnetic resistance in the MR device R_M.

Claims

1. A voltage detection circuit comprising:

a coil connected between positive and negative terminals of a battery and

a magnetoresistive device magnetically coupled to the coil.

2. A voltage detection circuit according to claim 1, further comprising amplification means for amplifying a signal from the magnetoresistive device.

3. A voltage detection circuit according to claim 1, further comprising a bridge circuit including the magnetoresistive device.

4. A voltage detection circuit according to claim 3, further comprising a differential amplification circuit connected between two output terminals of the bridge circuit.

5. A voltage detection circuit according to claim 1, wherein the magnetoresistive device includes:

a free layer having a direction of magnetization changeable by an external magnetic field;

a fixed layer having a fixed direction of magnetization; and

a nonmagnetic intermediate layer interposed between the free layer and the fixed layer.

6. A system comprising a plurality of voltage detection circuits respectively connected to a plurality of batteries;

wherein each of the voltage detection circuits comprises;

a coil connected between positive and negative terminals of a battery; and

a magnetoresistive device magnetically coupled to the coil.

7. A system according to claim 6, further comprising:

a charger section connected to the plurality of batteries through a first switch;

a load connected to the plurality of batteries through a second switch; and

a control section for controlling the first and second switches according to a result of detection from each of the voltage detection circuits.