Systems and methods for a high isolation current sensor

Patent metadata

Field	Value
Publication number	US-9958482-B1
Application number	US-201615384427-A
Country	US
Kind code	B1
Filing date	Dec 20, 2016
Priority date	Dec 20, 2016
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

Systems and methods are described herein for creating a high isolation integrated current sensor whereby a portion of a current to be sensed by a magnetic field sensing circuit is split within the current sensor. The current sensor includes a primary conductor configured to carry a first portion of a primary current and a semiconductor substrate having a first surface and a second opposing surface. The first surface supports a magnetic field sensing circuit. The current sensor includes a first insulation layer disposed over the first surface, a conductive layer disposed over the first insulation layer and at least two interconnects coupled between the primary conductor and the conductive layer. A second portion of the primary current can flow through the conductive layer and the magnetic field sensing circuit is configured to sense the second portion of primary current.

First claim

What is claimed:

1. A current sensor comprising:
a primary conductor configured to carry a first portion of a primary current;
a semiconductor substrate having a first surface and a second opposing surface, the first surface supporting a magnetic field sensing circuit, a first insulation layer disposed over the first surface, and a conductive layer disposed over the first insulation layer, wherein the primary conductor is spaced from the semiconductor substrate such that the primary conductor and the semiconductor substrate do not vertically overlap each other; and
at least two interconnects comprising wire bonds coupled between the primary conductor and the conductive layer, wherein a second portion of the primary current flows through the conductive layer, and wherein the magnetic field sensing circuit is configured to sense the second portion of the primary current.

2. The current sensor of claim 1 , wherein the conductive layer comprises one or both of a coil and a trace.

3. The current sensor of claim 1 , wherein a level of the second portion of the primary current is established in part based on a resistance value of the at least two interconnects.

4. The current sensor of claim 1 , further comprising a calibration circuit configured to calibrate a sensitivity of the magnetic field sensing circuit in response to a difference between a measured level of the second portion of the primary current and a predetermined level of the second portion of the primary current.

5. The current sensor of claim 1 , wherein the semiconductor substrate is supported by a lead frame or a printed circuit board in a die up configuration.

6. The current sensor of claim 1 , further comprising a shield layer disposed between the first surface of the semiconductor substrate and the first insulation layer or between the first insulation layer and the conductive layer.

7. The current sensor of claim 6 , wherein the shield layer is coupled to a reference potential of the magnetic field sensing circuit.

8. The current sensor of claim 6 , wherein the shield layer comprises one or more slits.

9. The current sensor of claim 6 , wherein the shield layer comprises one or both of copper and aluminum.

10. The current sensor of claim 1 , further comprising a second insulation layer disposed over the conductive layer.

11. The current sensor of claim 10 , wherein the first and second insulation layers comprise one of or a combination of two or more of a polyimide film, silicon dioxide, and a layer of adhesive.

12. The current sensor of claim 10 , wherein the first and second insulation layers have a thickness ranging from about 5 μm to about 50 μm.

13. The current sensor of claim 1 , wherein the conductive layer comprises one or both of a metalized tape and a metalized Mylar®.

14. The current sensor of claim 1 , wherein the primary conductor, the conductive layer, and the at least two interconnects comprise the same material.

15. The current sensor of claim 1 , wherein the magnetic field sensing circuit comprises a magnetic field sensing element comprising one or both of a Hall effect element and a magnetoresistance element.

16. The current sensor of claim 15 , wherein the magnetoresistance element comprises one of or a combination of two or more of Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance (AMR) element, a tunneling magnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ) element.

17. The current sensor of claim 1 , wherein the magnetic field sensing circuit is configured to sense a magnetic field in first and second directions, and wherein a difference between a strength of the magnetic field in the first and second directions is proportional to the second portion of the primary current.

18. The current sensor of claim 1 , wherein an output voltage of the current sensor is proportional to the primary current.

19. A current sensor comprising:
a lead frame comprising at least two leads coupled together to form a primary conductor to carry a first portion of a primary current and a signal lead spaced from the at least two leads to carry an output signal of the current sensor having a level indicative of a level of the primary current;
a semiconductor substrate having a first surface distal from the lead frame, the first surface supporting a magnetic field sensing circuit and a conductive layer electrically isolated from the magnetic field sensing circuit, the semiconductor substrate further having a second opposing surface proximal to the lead frame; and
at least two interconnects coupled between the primary conductor and the conductive layer, wherein a second portion of the primary current flows through the conductive layer and wherein the magnetic field sensing circuit comprises one or more magnetic field sensing elements to sense the second portion of the primary current;
wherein the magnetic field sensing circuit further comprises a calibration circuit configured to calibrate a sensitivity of the magnetic field sensing circuit in response to a difference between a measured level of the current sensor output signal for a selected primary current level and a predetermined level of the current sensor output signal for the selected primary current level.

20. The current sensor of claim 19 , wherein the conductive layer comprises one or both of a coil and a trace.

21. The current sensor of claim 19 , wherein a level of the second portion of the primary current is established in part based on a resistance value of the at least two interconnects.

22. The current sensor of claim 19 , wherein the at least two interconnects comprise wire bonds.

23. The current sensor of claim 19 , wherein the primary conductor and the at least two interconnects comprise the same material.

24. The current sensor of claim 19 , wherein the magnetic field sensing circuit comprises a magnetic field sensing element comprising one or both of a Hall effect element and a magnetoresistance element.

25. The current sensor of claim 24 , wherein the magnetoresistance element comprises one of or a combination of two or more of Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance (AMR) element, a tunneling magnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ) element.

26. The current sensor of claim 19 , wherein the magnetic field sensing circuit is configured to sense a magnetic field in first and second directions, and wherein a difference between a strength of the magnetic field in the first and second directions is proportional to the second portion of the primary current.

27. The current sensor of claim 19 , wherein an output voltage of the current sensor is proportional to the primary current.

28. The current sensor of claim 19 , wherein primary conductor is spaced from the semiconductor substrate such that the primary conductor and the semiconductor substrate do not vertically overlap each other.

Assignees

• Allegro Microsystems Llc

Inventors

• Latham Alexander

Classifications

• H10W90/756

  between a chip and a stacked lead frame, conducting package substrate or heat sink · CPC title

• H10W72/5473

  multiple bond wires connected to a common bond pad · CPC title

• H10W72/932

  Plan-view shape, i.e. in top view · CPC title

• H10W72/884

  Die-attach connectors and bond wires · CPC title

• G01R15/202

  using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08) · CPC title