Integrated sensor having a magnetic flux concentrator

• US 7,476,953 B2
• Filed: 02/04/2005
• Issued: 01/13/2009
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Pinelle, Sandra R., Dickinson, Richard, Taylor, William P., Doogue, Michael C.
• Primary Examiner(s): Pert; Evan
• Assistant Examiner(s): TRAN, TAN N
• Application Number:
  US11/051,124
• Publication Number:
  US 20060175674A1
• Time in Patent Office: 1,439 Days
• Field of Search: 257/421, 257/108, 257/414, 257/422, 257/423, 257/424, 257/425, 257/427
• US Class Current: 257/421
• CPC Class Codes: G01R 33/02 Measuring direction or magnitude of magnetic fields or magnetic flux G01R33/20 takes precedence

Abstract

An integrated sensor has a magnetic field sensing element and first and second relatively high magnetically permeable members forming a gap, wherein the magnetic field element is disposed within the gap. The magnetically permeable members provide an increase in the flux experienced by the magnetic field sensing element in response to a magnetic field. The integrated sensor can be used as a current sensor, a proximity detector, or a magnetic field sensor.

Claims

1. An integrated sensor, comprising:

a magnetic field sensing element having a maximum response axis and having first and second opposing surfaces;

a first member provided from a soft magnetic material, the first member having an end disposed proximate to the first opposing surface; and

a second member provided from a soft magnetic material, the second member having an end disposed proximate to the second opposing surface providing a gap generally oriented along a line between the ends of the first and second members, wherein the magnetic field sensing element is disposed within the gap, and wherein the gap is generally aligned with the maximum response axis of the magnetic field sensing element.

2. The integrated sensor of claim 1, further comprising a leadframe, wherein at least one of the first member or the second member is provided as a respective at least one leadframe portion.

3. The integrated sensor of claim 2, further including a weld that welds at least one of the first member or the second member to the leadframe.

4. The integrated sensor of claim 2, wherein the magnetic field sensing element, the first member, the second member, and the at least one leadframe portion are provided as a packaged integrated circuit.

5. The integrated sensor of claim 2, wherein the first member is provided as a first leadframe portion and the second member is provided as a second leadframe portion.

6. The integrated sensor of claim 2, wherein a portion of at least one of the first member or the second member comprises a plating upon the at least one leadframe portion.

7. The integrated sensor of claim 1, wherein the magnetic field sensing element is disposed generally in a plane and wherein at least a portion of the first member and at least a portion of the second member are disposed generally in the plane.

8. The integrated sensor of claim 1, wherein the magnetic field sensing element is disposed generally in a first plane, at least a portion of the first member is disposed generally in a second plane, and at least a portion of the second member is disposed generally in a third plane, and wherein the second and third planes are generally parallel to and on opposite sides of the first plane.

9. The integrated sensor of claim 1, wherein a size of the gap is selected in accordance with a predetermined flux density at the magnetic field sensing element.

10. The integrated sensor of claim 1, wherein the first member and the second member are adapted to concentrate a magnetic flux in the gap in a direction generally along the maximum response axis of the magnetic field sensing element in response to an electrical current.

11. The integrated sensor of claim 10, wherein the electrical current is in a conductive trace on a circuit board.

12. The integrated sensor of claim 1, further comprising:

a substrate coupled to the magnetic field sensing element; and

an electronic circuit disposed upon the substrate.

13. The integrated sensor of claim 12, wherein a least a portion of the first member and the second member is deposited onto the substrate.

14. The integrated sensor of claim 12, wherein the magnetic field sensing element is disposed upon the substrate.

15. The integrated sensor of claim 1, wherein the ends of the first and second members have a shape selected in accordance with a predetermined flux density at the magnetic field sensing element.

16. The integrated sensor of claim 15, wherein the ends of the first and second members have a tapered shape.

17. The integrated sensor of claim 1, wherein the magnetic field sensing element is a magnetoresistance element.

18. The integrated sensor of claim 1, wherein the magnetic field sensing element is a Hall element.

19. The integrated sensor of claim 1, wherein the magnetic field sensing element is a vertical Hall element.

20. The integrated sensor of claim 1, wherein the first member and the second member are adapted to concentrate a magnetic flux in the gap in a direction generally along the maximum response axis of the magnetic field sensing element in response to a proximity of a ferromagnetic object.

21. The integrated sensor of claim 1, wherein the first member and the second member are adapted to concentrate a magnetic flux in the gap in a direction generally along the maximum response axis of the magnetic field sensing element in response to a magnetic field external to the integrated sensor.

22. The integrated sensor of claim 1, wherein the magnetic field sensing element is disposed generally in a first plane, at least a portion of the first member is disposed generally in a second plane generally parallel to the first plane, and at least a portion of the second member is disposed generally in a third plane generally parallel to the first plane.

23. The integrated sensor of claim 1, further comprising a leadframe having a plurality of leads, wherein a portion of at least one of the first member or the second member comprises at least a respective portion of a respective one of the plurality of leads.

24. The integrated sensor of claim 1, further comprising a substrate supporting the magnetic field sensing element on a surface of the substrate, wherein the maximum response axis of the magnetic field sensing element is substantially perpendicular to the surface of the substrate.

25. An integrated sensor, comprising:

a substrate;

a leadframe proximate to the substrate, the leadframe having a plurality of leads and a member; and

a magnetic field sensing element disposed upon the substrate, the magnetic field sensing element having a maximum response axis and having a surface;

wherein the member is provided from a soft magnetic material, the member having an end disposed proximate to the surface of the magnetic field sensing element, wherein the member is adapted to concentrate a magnetic flux in a direction generally along the maximum response axis of the magnetic field sensing element in response to a selected one of an electrical current, a proximity of a ferromagnetic object, or a magnetic field external to the integrated sensor.

26. The integrated sensor of claim 25, further comprising:

a weld that welds the portion of the member to the leadframe.

27. The integrated sensor of claim 25, wherein the substrate, the magnetic field sensing element, and the member are provided as a packaged integrated circuit.

28. The integrated sensor of claim 25, wherein the magnetic field sensing element is disposed generally in a plane, and wherein at least a portion of the member is disposed generally in the plane.

29. The integrated sensor of claim 25, wherein the magnetic field sensing element is disposed generally in a first plane, and at least a portion of the member is disposed generally in a second plane different than the first plane, wherein the second plane is generally parallel to the first plane.

30. The integrated sensor of claim 25, further comprising an electronic circuit disposed upon the substrate.

31. The integrated sensor of claim 25, wherein the electrical current is in a conductive trace on a circuit board.

32. The integrated sensor of claim 25, wherein an end of the member has a shape selected in accordance with a predetermined flux density at the magnetic field sensing element.

33. The integrated sensor of claim 32, wherein the end of the member has a tapered shape.

34. The integrated sensor of claim 25, wherein another portion of the member comprises a deposition disposed upon the substrate.

35. The integrated sensor of claim 25, wherein the substrate supports the magnetic field sensing element on a surface of the substrate, wherein, the maximum response axis of the magnetic field sensing element is substantially perpendicular to the surface of the substrate, and wherein the member provides an increase in flux density in a direction generally perpendicular to the surface of the substrate.