Electrical device including a voltage regulator mounted on a variable resistor

• US 6,914,416 B2
• Filed: 12/26/2002
• Issued: 07/05/2005
• Est. Priority Date: 04/15/1998
• Status: Expired due to Term

• Current Assignee: Littelfuse Incorporated
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Thomas, Brian, Beaufils, Jean-Marc, Dallemange, Bernard, Gozlan, Gilles, Luan, Jiyuan, Thornton, Neill, Toth, James, Cogan, Adrian
• Primary Examiner(s): Sparks, Donald
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US10/331,113
• Publication Number:
  US 20030132732A1
• Time in Patent Office: 922 Days
• Field of Search: 320/136, 320/135, 361/707, 361/708, 361/718, 361/719, 361/720, 361/712, 361/18, 361/21, 361/24, 361/161, 361/274.3, 361/282, 257/706, 257/707, 257/712, 257/713, 257/782, 438/379, 438/382
• US Class Current: 320/136
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/16 the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/1301 Thyristor
• CPC Class Codes: H01L 2924/13062 Junction field-effect transistor [JFET]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02H 9/042 comprising means to limit the absorbed power or indicate damaged over-voltage protection device
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence

Abstract

A protection circuit for use with a charger and a chargeable element, such as a rechargeable lithium ion battery, comprises a shunt regulator having a threshold ON voltage coupled in parallel across the chargeable element, and a temperature-dependent resistor, e.g., a positive temperature coefficient device, coupled in series between the charger and the chargeable element. The temperature dependent resistor is thermally and electrically coupled to the shunt regulator, wherein the first variable resistor limits current flowing through the shunt regulator if the current reaches a predetermined level less than that which would cause failure of the regulator, due to ohmic heating of the regulator.

Claims

1. A method for manufacturing a circuit protection device, comprising:

forming a variable resistor having a thermally and electrically conductive surface; and

securing a thermally and electrically conductive surface of a voltage regulator to the thermally and electrically conductive surface of the variable resistor such that the voltage regulator is thermally coupled to the variable resistor,

wherein the variable resistor is formed by

forming a substrate comprising a positive temperature coefficient material,

applying a first electrically conductive layer to a first surface of the substrate,

appying a first electrically insulating layer on the first conductive layer, and

removing a portion of the first insulating layer to expose a portion of the first conductive layer,

wherein the voltage regulator is secured to the variable resistor by

positioning solder material on the exposed portion of the first conductive layer,

positioning the thermally and electrically conductive surface of the voltage regulator in contact with the solder material, and

heating the solder material to cause flow of the solder material,

the voltage regulator comprising

a transistor formed on a die, and

a heat sink, the heat sink having a first surface and a second surface, the second surface comprising the thermally and electrically conductive surface of the voltage regulator,

the die attached to the first heat sink surface such that the transistor is thermally coupled to the heat sink, and

wherein the removed portion of the first insulating layer forms a window around the exposed portion of the first conductive surface, the window being sized such that, during flow of the solder material, the heat sink will self-center within the window.

2. The method of claim 1, further comprising

applying a second electrically conductive layer to a second surface of the substrate,

applying a second electrically insulating layer on the second conductive layer, and

removing a portion of the second insulating layer to expose a portion of the second conductive layer.

3. The method of claim 2, further comprising

electrically connecting a first terminal of the circuit protection device to the exposed portion of the second conductive layer,

electrically connecting a second terminal of the circuit protection device to a first terminal of the transistor, and

electrically connecting a third terminal of the circuit protection device to a second terminal of the transistor,

the transistor having a third terminal disposed on a surface of the die so as to be in electrical contact with the heat sink.