Switch controlled current sensing using a hall effect sensor

• US 8,963,535 B1
• Filed: 06/30/2009
• Issued: 02/24/2015
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Melanson, John L.
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): Astacio-Oquendo, Giovanni
• Application Number:
  US12/495,142
• Time in Patent Office: 2,065 Days
• Field of Search: 324/117.H, 324/207.2, 324/244, 324/251, 324/252
• US Class Current: 324/117.H
• CPC Class Codes: G01R 15/202 using Hall-effect devices Hall elements in arrangements for measuring electrical power G01R21/08
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: H03K 17/90 by the use, as active elements, of galvano-magnetic devices, e.g. Hall-effect devices H03K17/95, H03K17/97 take precedence

Abstract

An electronic system includes a Hall sensor to sense a controlled current. The Hall sensor is positioned proximate to a signal path and develops a voltage that includes a component corresponding to a controlled current. A controller generates a switch control signal to control conductivity of a switch, and the switch controls drive current for a load. The controller receives information either directly or indirectly from the Hall sensor corresponding to the controlled current and utilizes the information from the Hall sensor to control conductivity of the switch. Controlling conductivity of the switch controls the drive current for the load. The frequency of the switch control signal is sufficiently higher than a Hall sensor noise voltage to allow the controller to sufficiently cancel out the noise voltage for control purposes.

Claims

1. An apparatus comprising:

an integrated circuit comprising;

a Hall sensor configured to sense a magnetic field of a controlled current; and

a controller coupled to the Hall sensor, wherein at least during operation the controller is configured to;

(i) receive information from the Hall sensor, (ii) sample the information at a sample frequency sufficiently greater than a frequency of Hall sensor noise voltage to effectively cancel out the Hall sensor noise voltage from the information received from the Hall sensor, and (ii) use the information to determine a time to cause a switch, which controls the controlled current, to conduct.

2. The apparatus of claim 1 wherein the controller is configured to:

sense a voltage V₀ from the Hall sensor while the switch is nonconductive (“

off”

);

generate a switch control signal at time t₁ to cause the switch to conduct (“

on”

) and the controlled current to flow;

sense a voltage V₁ from the Hall sensor while the switch is conductive; and

determine a time t₃ to turn the switch “

off”

based on a time t₂, wherein time t₂ is when the sensed voltage V₁ plus the sensed voltage V₀ equals a target voltage; and

generate the switch control signal at time t₃ to turn the switch “

off”

.

3. The apparatus of claim 2 wherein the times t₂−

t₁=t₃−

t₂.

4. The apparatus of claim 1 further comprising:

a signal trace located within proximity of the Hall sensor to allow the Hall sensor to sense the magnetic field of the controlled current.

5. The apparatus of claim 4 wherein the signal trace is included in a printed circuit board coupled to the integrated circuit.

6. The apparatus of claim 4 further comprising:

an integrated circuit package containing the integrated circuit, wherein the integrated circuit includes a lead frame, wherein the signal trace is attached to the lead frame.

7. The apparatus of claim 1 further comprising:

a circuit board coupled to the integrated circuit; and

the switch coupled to the circuit board via a signal trace, wherein the signal trace is configured to conduct the controlled current in proximity to the Hall sensor to allow the Hall sensor to sense the controlled current.

8. The apparatus of claim 7 wherein the switch comprises a field effect transistor and the signal trace is coupled in series with the switch.

9. The apparatus of claim 1 further comprising an analog-to-digital converter to convert the information received from the Hall sensor into a digital signal, wherein the information comprises the digital signal, and the digital signal represents a first voltage at a first time that includes a component associated with the controlled current and a component associated with Hall sensor noise and the digital signal represents a second voltage at a second time that includes the component associated with the Hall sensor noise and does not include the component associated with the controlled current, and the controller is further configured to determine a difference between the first voltage and the second voltage to determine a third voltage that corresponds to a value of the controlled current.

10. The apparatus of claim 9 wherein the component of the first voltage associated with the controlled current is directly proportional to a drive current for the load.

11. The apparatus of claim 1 wherein the apparatus further comprises a load, the load comprises at least one light emitting diode.

12. The apparatus of claim 1 wherein the information comprises an analog signal representing a first voltage at a first time that includes a component associated with the controlled current and a component associated with Hall sensor noise and the signal represents a second voltage at a second time that includes the component associated with the Hall sensor noise and does not include the component associated with the controlled current, and the controller is further configured to determine a difference between the first voltage and the second voltage to determine a third voltage that corresponds to a value of the controlled current.

13. The apparatus of claim 1 wherein the controller is configured to control the switch to control current in a load.

14. The apparatus of claim 1 wherein the switch is included in a switching power converter and the controller is configured to control the switch to provide power factor correction for the switching power converter.

15. The apparatus of claim 14 further comprising:

the switching power converter coupled to the controller.

16. A method comprising:

in an integrated circuit;

sensing a magnetic field of a controlled current using a Hall sensor in the integrated circuit;

receiving information from the Hall sensor;

sampling the information received from the Hall sensor at a frequency sufficiently greater than a frequency of Hall sensor noise voltage to effectively cancel out the Hall sensor noise voltage from the information received from the Hall sensor; and

utilizing the information to determine a time to cause a switch, which controls the controlled current, to conduct.

17. The method of claim 16 further comprising:

sensing a voltage V0 from the Hall sensor while the switch is nonconductive (“

off”

);

generating a switch control signal at time t1 to cause the switch to conduct (“

on”

) and the controlled current to flow;

sensing a voltage V1 from the Hall sensor while the switch is conductive; and

determining a time t3 to turn the switch “

off”

based on a time t2, wherein time t2 is when the sensed voltage V1 plus the sensed voltage V0 equals a target voltage; and

generating the switch control signal at time t3 to turn the switch “

off”

.

18. The method of claim 17 wherein the times t₂−

t₁=t₃−

t₂.

19. The method of claim 16 further comprising:

conducting the controlled current in a signal trace located within proximity of the Hall sensor to allow the Hall sensor to sense the magnetic field of the controlled current.

20. The method of claim 19 wherein the signal trace is included in a printed circuit board coupled to the integrated circuit.

21. The method of claim 19 wherein the signal trace is attached to a lead frame of an integrated circuit.

22. The method of claim 19 wherein the switch comprises a field effect transistor and the signal trace is coupled in series with the switch.

23. The method of claim 16 further comprising converting the information received from the Hall sensor into a digital signal, wherein the digital signal represents a first voltage at a first time that includes a component associated with the controlled current and a component associated with Hall sensor noise and the digital signal represents a second voltage at a second time that includes the component associated with the Hall sensor noise and does not include the component associated with the controlled current, and the method further comprises:

determine a difference between the first voltage and the second voltage to determine a third voltage that corresponds to a value of the controlled current.

24. The method of claim 23 wherein the component of the first voltage associated with the controlled current is directly proportional to a drive current for the load.

25. The method of claim 16 wherein the load comprises at least one light emitting diode.

26. The method of claim 16 wherein the information comprises an analog signal representing a first voltage at a first time that includes a component associated with the controlled current and a component associated with Hall sensor noise and the analog signal represents a second voltage at a second time that includes the component associated with the Hall sensor noise and does not include the component associated with the controlled current, and the method further comprises:

determine a difference between the first voltage and the second voltage to determine a third voltage that corresponds to a value of the controlled current.

27. The method of claim 16 wherein utilizing the information to determine a time to cause a switch to conduct further comprises:

controlling the switch to control power factor correction of a switching power converter.

28. The method of claim 16 further comprising:

conducting the controlled current in a signal trace located within proximity of the Hall sensor to allow the Hall sensor to sense the magnetic field of the controlled current, wherein the signal trace is included in a printed circuit board coupled to the integrated circuit.

29. The method of claim 28 wherein the signal trace is attached to a lead frame of an integrated circuit.

30. An apparatus comprising:

an integrated circuit that includes;

means for sensing a magnetic field of a controlled current using a Hall sensor in the integrated circuit;

means for receiving information from the Hall sensor;

means for sampling the information received from the Hall sensor at a frequency sufficiently greater than a frequency of Hall sensor noise voltage to effectively cancel out the Hall sensor noise voltage from the information received from the Hall sensor; and

means for utilizing the information to determine a time to cause a switch, which controls the controlled current, to conduct.

31. An apparatus comprising:

an integrated circuit comprising;

a Hall sensor configured to sense a magnetic field of a controlled current; and

a controller coupled to the Hall sensor, wherein the controller is configured to;

sense a voltage V₀ from the Hall sensor while the switch is nonconductive (“

off”

);

generate a switch control signal at time t₁ to cause the switch to conduct (“

on”

) and the controlled current to flow;

sense a voltage V₁ from the Hall sensor while the switch is conductive; and

determine a time t₃ to turn the switch “

off”

based on a time t₂, wherein time t₂ is when the sensed voltage V₁ plus the sensed voltage V₀ equals a target voltage; and

generate the switch control signal at time t₃ to turn the switch “

off”

.

32. The apparatus of claim 31 wherein the controller is further configured to effectively cancel out Hall sensor noise voltage from the information received from the Hall sensor to determine a time to cause the switch, which controls the controlled current, to conduct.

33. The apparatus of claim 32 wherein a frequency of the Hall sensor noise voltage is sufficiently less than a sample frequency of the information received from the Hall sensor to effectively cancel out Hall sensor noise voltage from the information received from the Hall sensor.

34. The apparatus of claim 31 wherein the times t₂−

t₁=t₃−

t₂.

35. The apparatus of claim 31 further comprising:

a signal trace located within proximity of the Hall sensor to allow the Hall sensor to sense the magnetic field of the controlled current, wherein the signal trace is included in a printed circuit board coupled to the integrated circuit.

36. The apparatus of claim 35 further comprising:

an integrated circuit package containing the integrated circuit, wherein the integrated circuit includes a lead frame, wherein the signal trace is attached to the lead frame.

37. The apparatus of claim 31 wherein the apparatus further comprises a load, the load comprises at least one light emitting diode.

38. The apparatus of claim 31 wherein the switch is included in a switching power converter and the controller is configured to control the switch to provide power factor correction for the switching power converter.

39. A method comprising:

in an integrated circuit;

sensing a magnetic field of a controlled current using a Hall sensor in the integrated circuit;

sensing a voltage V0 from the Hall sensor while the switch is nonconductive (“

off”

);

generating a switch control signal at time t1 to cause the switch to conduct (“

on”

) and the controlled current to flow;

sensing a voltage V1 from the Hall sensor while the switch is conductive; and

determining a time t3 to turn the switch “

off”

based on a time t2, wherein time t2 is when the sensed voltage V1 plus the sensed voltage V0 equals a target voltage; and

generating the switch control signal at time t3 to turn the switch “

off”

.

40. The method of claim 39 wherein utilizing the information to determine a time to cause a switch further comprises:

effectively cancelling out Hall sensor noise voltage received from the Hall sensor to determine a time to cause the switch, which controls the controlled current, to conduct.

41. The method of claim 40 further comprising:

sampling the voltages received from the Hall sensor at a frequency sufficiently greater than a frequency of the Hall sensor noise voltage to effectively cancel out the Hall sensor noise voltage received from the Hall sensor.

42. The method of claim 39 wherein the times t₂−

t₁=t₃−

t₂.

43. The method of claim 39 wherein the load comprises at least one light emitting diode.

44. The method of claim 39 wherein utilizing the information to determine a time to cause a switch to conduct further comprises:

controlling the switch to control power factor correction of a switching power converter.