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US6297619B1 Expired / Lapsed US ⏱️ 0.0 years remaining

Secondary battery cell protection circuit

Assignee: Mitsumi Electric Co Ltd
•
Filing: 1999-09-10
•
Granted: 2001-10-02
•
Expires: 2019-09-10
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Abstract

Abstract A secondary battery cell protection circuit protects a charge control FET, a discharge control FET, and a secondary battery cell from destruction due to use of a charger of greater than rated voltage to charge the secondary battery cell. The secondary battery cell protection circuit has a charger voltage detection circuit, a first charge circuit control circuit for cutting off a charge circuit when the charger voltage detection circuit detects a charger voltage in excess of a predetermined value, and a second charge control circuit for cutting off a charge circuit when the over-charge detection circuit detects a secondary battery cell charge voltage in excess of a predetermined value. When the charge control FET is OFF, a load voltage proportionate to the charge voltage of the charger appears at a −B terminal and is applied to the emitter of a transistor, activating the transistor. A current proportionate to the charge voltage of the charger then flows to the transistor. If at this time the charger voltage is above the rated voltage, then a resistor is set so that a voltage drop of the resistor exceeds a base voltage. As a result, when the charger voltage is above the rated voltage the charge voltage of the secondary battery cell declines thereafter and a charge control FET drive transistor remains in an OFF state even after the charge voltage is at or below a release charge voltage.

Inventors

  • 👤 Yukihiro Terada

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 09:08
CPC Classifications
H; H02; H02J; H02J7/00; H02J7/60; H02J7/663; H02J7/61; H02J7/63

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 96 words
A secondary battery cell protection circuit for protecting a secondary battery cell according to the voltage of the secondary battery cell, comprising: a charger voltage detection circuit detecting a charger voltage; a first charge circuit control circuit cutting off a charge circuit when the charger voltage detection circuit detects a charger voltage in excess of a predetermined value; and an over-discharge detection circuit and an over-charge detection circuit and a charge control field-effect transistor wherein the charge control field-effect transistor is turned off when the over-charge detection circuit detects an overcharge of the secondary battery cell.
Claim 2
Dependent Claim 96 words
A secondary battery cell protection circuit for protecting a secondary battery cell according to the voltage of the secondary battery cell, comprising: a charger voltage detection circuit detecting a charger voltage; a first charge circuit control circuit cutting off a charge circuit when the charger voltage detection circuit detects a charger voltage in excess of a predetermined value; and an over-discharge detection circuit and an over-charge detection circuit and a charge control field-effect transistor wherein the charge control field-effect transistor is turned off when the over-charge detection circuit detects an overcharge of the secondary battery cell.
Claim 3
Dependent Claim 59 words
The secondary battery protection circuit as claimed in claim 1 , wherein the first the first charge circuit control circuit controls the charge control field-effect transistor (FET) Q 2 inserted in series into the charge circuit and shuts off the charge control FET when the charger voltage detection circuit detects a chargers voltage in excess of the predetermined value.
Claim 4
Dependent Claim 53 words
The secondary battery protection circuit as claimed in claim 2 , further comprising the over-charge detection circuit and a second charge circuit control circuit, the second charge circuit control circuit cutting off the charge circuit when the over-charge detection circuit detects a secondary battery cell charge voltage in excess of a predetermined value.
Claim 5
Dependent Claim 52 words
The secondary battery cell protection circuit as claimed in claim 3 , wherein the first charge circuit control circuit and the second charge circuit control circuit, respectively, include a switching element which cuts off the charge circuit, the switching element being used for both the first and second charge circuit control circuits.
Claim 6
Dependent Claim 53 words
The secondary battery protection circuit as claimed in claim 1 , further comprising the over-charge detection circuit and a second charge circuit control circuit, the second charge circuit control circuit cutting off the charge circuit when the over-charge detection circuit detects a secondary battery cell charge voltage in excess of a predetermined value.
Claim 7
Dependent Claim 52 words
The secondary battery cell protection circuit as claimed in claim 5 , wherein the first charge circuit control circuit and the second charge circuit control circuit, respectively, include a switching element which cuts off the charge circuit, the switching element being used for both the first and second charge circuit control circuits.
Claim 8
Dependent Claim 26 words
The secondary battery cell protection circuit as claimed in claim 1 , wherein the charger voltage detection circuit functions when the charge circuit is cut off.

References Cited (Backward Citations)

US6064179A Cited
US5789900A Cited
JPH0956056A Cited
US6075346A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 2004-10-01 2005-04-02 2005-10-02 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2008-10-01 2009-04-02 2009-10-02 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2012-10-01 2013-04-02 2013-10-02 $7700.00 Window Closed / Lapsed

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