Integrated sensor having a magnetic flux concentrator

• US 20060175674A1
• Filed: 02/04/2005
• Published: 08/10/2006
• 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: Taylor, William P., Dickinson, Richard, Doogue, Michael C.
• Granted Patent: US 7,476,953 B2
• Time in Patent Office: Days
• 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. A integrated sensor, comprising:

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

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 between the ends of the first and second members, wherein the magnetic field sensing element is disposed within the gap.

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

3. The integrated sensor of claim 2, wherein the at least one leadframe portion is provided with a weld to a leadframe.

4. The integrated sensor of claim 2, wherein the magnetic field sensing element, the substrate, 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 and the second member is plated onto 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 the gap is generally aligned with the maximum response axis of the magnetic field sensing element.

10. 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.

11. 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.

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

13. The integrated sensor of claim 1, further comprising a substrate coupled to the magnetic field sensing element and adapted to provide an electronic circuit.

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

15. The integrated sensor of claim 13, wherein the magnetic field sensing element is disposed on the substrate.

16. 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.

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

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

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

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

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 proximity of a ferromagnetic object.

22. 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.

23. An integrated sensor, comprising:

a magnetic field sensing element having a maximum response axis and having a surface; and

a member 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 provided as a leadframe portion.

24. The integrated sensor of claim 23, wherein the leadframe portion is provided with a weld to a leadframe.

25. The integrated sensor of claim 23, wherein the magnetic field sensing element, the substrate, the first member, the second member, and the leadframe portion are provided as a packaged integrated circuit.

26. The integrated sensor of claim 23, 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.

27. The integrated sensor of claim 23, 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, wherein the second plane is generally parallel to the first plane.

28. The integrated sensor of claim 23, further comprising a substrate coupled to the magnetic field sensing element and adapted to provide an electronic circuit.

29. The integrated sensor of claim 28, wherein a least a portion of the member is deposited onto the substrate.

30. The integrated sensor of claim 23, 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 an electrical current.

31. The integrated sensor of claim 30, wherein the electrical current is in a conductive trace on a circuit board.

32. The integrated sensor of claim 23, 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 proximity of a ferromagnetic object.

33. The integrated sensor of claim 23, 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 magnetic field external to the integrated sensor.

34. A dual leadframe, comprising:

a first leadframe; and

a second leadframe coupled to the first leadframe, at least a portion of the second leadframe provided from a soft magnetic material.

35. The dual leadframe of claim 34, wherein the first leadframe is coupled to the second leadframe with a weld.

36. The dual leadframe of claim 34, wherein a least one lead portion of the dual leadframe is provided from the soft magnetic material.

37. The dual leadframe of claim 34, wherein the first leadframe is coupled to the second leadframe with a non-conductive bar.

38. A leadframe, comprising:

a first leadframe portion; and

a second leadframe portion adjacent to the first leadframe portion, wherein the second leadframe portion has a relatively high magnetic permeability.

39. The leadframe of claim 38, wherein the first leadframe portion is coupled to the second leadframe portion with a weld.

40. The leadframe of claim 38, wherein a least one lead portion of the leadframe is provided from the soft material.

41. The leadframe of claim 38, wherein the second leadframe portion is plated with a soft magnetic material.