CURRENT SENSOR

• US 20060152210A1
• Filed: 01/20/2006
• Published: 07/13/2006
• Est. Priority Date: 08/26/2003
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Taylor, William P., Doogue, Michael C., Mangtani, Vijay
• Granted Patent: US 7,075,287 B1
• Time in Patent Office: Days
• US Class Current: 324/117.H
• CPC Class Codes: G01R 1/36 Overload-protection arrangements or circuits for electric measuring instruments
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: H01L 2224/37147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/40095 Kinked
• CPC Class Codes: H01L 2224/40245 the item being metallic
• 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 2224/73221 Strap and wire connectors
• CPC Class Codes: H01L 2224/84801 Soldering or alloying
• CPC Class Codes: H01L 2224/8485 using a polymer adhesive, e.g. an adhesive based on silicone, epoxy, polyimide, polyester
• CPC Class Codes: H01L 24/37 of an individual strap connector
• CPC Class Codes: H01L 24/40 of an individual strap connector
• CPC Class Codes: H01L 24/84 using a strap connector
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01322 Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/1306 Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/14 Integrated circuits
• CPC Class Codes: H01L 2924/181 : Encapsulation

Abstract

An integrated circuit current sensor includes a lead frame having at least two leads coupled to provide a current conductor portion, and a substrate having a first surface in which is disposed one or more magnetic field sensing elements, with the first surface being proximate to the current conductor portion and a second surface distal from the current conductor portion. In one particular embodiment, the substrate is disposed having the first surface of the substrate above the current conductor portion and the second surface of the substrate above the first surface. In this particular embodiment, the substrate is oriented upside-down in the integrated circuit in a flip-chap arrangement. The integrated circuit includes an overcurrent circuit responsive to a voltage drop generated by a current.

Claims

1. An integrated circuit, comprising:

a lead frame portion having a plurality of leads;

a current conductor portion comprising at least two of the plurality of leads;

a substrate having first and second opposing surfaces, the first surface proximate to the current conductor portion and the second surface distal from the current conductor portion;

one or more magnetic field sensing elements disposed proximate to the current conductor portion;

a current sensing circuit disposed on the first surface of the substrate and coupled to the one or more magnetic field sensing elements, wherein the current sensing circuit is adapted to provide an output signal indicative of a current flowing through the current conductor portion; and

an overcurrent circuit disposed on the first surface of the substrate, wherein the overcurrent circuit is adapted to sense a voltage drop associated with a current and further adapted to provide an output signal in response to the voltage drop, wherein the output signal is indicative of the current sensed by the overcurrent circuit being above a predetermined current.

2. The integrated circuit of claim 1, wherein the first surface of the substrate includes at least two conductive regions coupled to the overcurrent circuit, and wherein the current conductor portion includes at least two features adapted to contact the at least two conductive regions.

3. The integrated circuit of claim 1, wherein the first surface of the substrate includes at least two conductive regions coupled to the overcurrent circuit, and wherein the integrated circuit further comprises at least two wire bonds coupled between the at least two conductive regions and the current conductor portion.

4. The integrated circuit of claim 1, further comprising a second substrate disposed proximate to the current conductor portion, wherein the one or more magnetic field sensing elements are disposed on the second substrate.

5. The integrated circuit of claim 1, wherein the overcurrent circuit is coupled to the current conductor portion, wherein the voltage drop is associated with the current flowing through the current conductor portion, and wherein the output signal is indicative of the current flowing through the current conductor portion being above a predetermined current.

6. The integrated circuit of claim 1, wherein the overcurrent circuit is coupled to at least two of the plurality of leads, and wherein the voltage drop is associated with the current flowing through the current conductor portion.

7. The integrated circuit of claim 1, wherein the overcurrent circuit is coupled to at least two of the plurality of leads.

8. The integrated circuit of claim 1, wherein the output signal provided by the overcurrent circuit is adapted to affect the output signal provided by the current sensing circuit.

9. The integrated circuit of claim 1, wherein the output signal generated by the overcurrent circuit is a digital output signal having first and second states, wherein one of the first and second states is indicative of the current being above the predetermined current and the other one of the first and second states is indicative of the current being below the predetermined current.

10. The integrated circuit of claim 1, wherein the current conductor portion is a first current conductor portion, and wherein the integrated circuit further comprises:

a second current conductor portion deposited on the first surface of the substrate, disposed proximate to the one or more magnetic field transducers, and coupled to the first current conductor portion, wherein at least a portion of the current flowing through the first current conductor portion also flows through the second current conductor portion.

11. The integrated circuit of claim 1, wherein the substrate is disposed having the first surface of the substrate above the current conductor portion and the second surface of the substrate above the first surface of the substrate when the plurality of leads is normally mounted to an uppermost surface of a circuit board.

12. The integrated circuit of claim 1, wherein the substrate is disposed having the second surface of the substrate above the current conductor portion and the first surface of the substrate above the second surface of the substrate when the plurality of leads is normally mounted to a uppermost surface of a circuit board.

13. The integrated circuit of claim 1, wherein the substrate has at least one bonding pad coupled to a corresponding one of the plurality of leads.

14. The integrated circuit of claim 1, wherein the substrate is coupled to at least one of the plurality of leads with a respective at least one of a solder ball, a gold bump, a eutectic or high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film.

15. A method of manufacturing an integrated circuit, comprising:

providing a lead frame portion having a plurality of leads comprising at least two leads forming a current conductor portion;

providing a substrate having first and second opposing surfaces;

forming one or more magnetic field sensing elements;

mounting the substrate to the lead frame portion so that the first surface of the substrate is proximate to the current conductor portion and the second surface of the substrate is distal from the current conductor portion;

forming a current sensing circuit on the first surface of the substrate, wherein the current sensing circuit is adapted to provide an output signal indicative of a current flowing through the current conductor portion; and

forming an overcurrent circuit on the first surface of the substrate, wherein the overcurrent circuit is adapted to sense a voltage drop associated with a current and further adapted to provide an output signal in response to the voltage drop, wherein the output signal is indicative of the current sensed by the overcurrent circuit being above a predetermined current.

16. The method of claim 15, wherein the first surface of the substrate includes at least two conductive regions coupled to the overcurrent circuit, and wherein the current conductor portion includes at least two features adapted to contact the at least two conductive regions.

17. The method of claim 15, wherein the first surface of the substrate includes at least two conductive regions coupled to the overcurrent circuit, and wherein the method further comprises forming at least two wire bonds coupled between the at least two conductive regions and the current conductor portion.

18. The method of claim 15, further comprising:

forming the one or more magnetic field sensing elements on a second substrate; and

mounting the second substrate proximate to the current conductor portion.

19. The method of claim 15, wherein the overcurrent circuit is coupled to the current conductor portion, wherein the voltage drop is associated with the current flowing through the current conductor portion, and wherein the output signal is indicative of the current flowing through the current conductor portion being above a predetermined current.

20. The method of claim 15, wherein the overcurrent circuit is coupled to at least two of the plurality of leads, and wherein the voltage drop is associated with the current flowing through the current conductor portion.

21. The integrated circuit of claim 15, wherein the overcurrent circuit is coupled to at least two of the plurality of leads.

22. The method of claim 15, wherein the output signal provided by the overcurrent circuit is adapted to affect the output signal provided by the current sensing circuit.

23. The method of claim 15, wherein the output signal generated by the overcurrent circuit is a digital output signal having first and second states, wherein one of the first and second states is indicative of the current being above the predetermined current and the other one of the first and second states is indicative of the current being below the predetermined current.

24. The method of claim 15, wherein the current conductor portion is a first current conductor portion, and wherein the method further comprises:

depositing a second current conductor portion on the first surface of the substrate, disposed proximate to the one or more magnetic field sensing elements and coupled to the first current conductor portion, wherein at least a portion of the current flowing through the first current conductor portion also flows through the second current conductor portion.

25. The method of claim 15, wherein the mounting the substrate comprises mounting the substrate such that the first surface of the substrate is above the current conductor portion and the second surface of the substrate is above the first surface of the substrate when the plurality of leads is normally mounted to an uppermost surface of a circuit board.

26. The method of claim 15, wherein the mounting the substrate comprises mounting the substrate such that the second surface of the substrate is above the current conductor portion and the first surface of the substrate is above the second surface of the substrate when the plurality of leads is normally mounted to an uppermost surface of a circuit board.

27. The method of claim 15, wherein the substrate has at least one bonding pad coupled to a corresponding one of the plurality of leads.

28. The method of claim 15, wherein the mounting the substrate to the lead frame portion comprises coupling the substrate to at least one of the plurality of leads with a respective at least one of a solder ball, a gold bump, a eutectic or high lead solder bump, a no-lead solder bump, a gold stud bump, a polymeric conductive bump, an anisotropic conductive paste, or a conductive film.