TWO-TERMINAL LINEAR SENSOR

• US 20090224754A1
• Filed: 03/06/2008
• Published: 09/10/2009
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Thomas, Monica J., Lamarre, Jonathan
• Granted Patent: US 8,054,071 B2
• Time in Patent Office: Days
• US Class Current: 324/251
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01R 33/0023 Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration G01R33/0017 takes precedence
• CPC Class Codes: G01R 33/0035 Calibration of single magnetic sensors, e.g. integrated calibration
• CPC Class Codes: G01R 33/07 Hall effect devices
• CPC Class Codes: G01R 33/09 Magnetoresistive devices

Abstract

A magnetic field sensor includes a linear magnetic field sensor to produce a voltage proportional to a sensed magnetic field and an interface having only two terminals for external connections. The two terminals of the interface include a power supply terminal and a ground terminal. The interface includes a voltage-controlled current generating device that is connected between the two terminals and is controlled by the voltage to provide a current signal that is proportional to the sensed magnetic field.

Claims

1. A magnetic field sensor, comprising:

a linear magnetic field sensor to sense a magnetic field and to produce a voltage proportional to the sensed magnetic field; and

an interface coupled to the linear magnetic field sensor and having only two terminals including a power supply terminal and a ground terminal;

wherein the interface includes a voltage-controlled current generating device connected between the two terminals, controllable by the voltage to provide a current proportional to the sensed magnetic field.

2. The magnetic field sensor of claim 1 wherein the linear magnetic field sensor comprises a Hall-effect element to sense the magnetic field.

3. The magnetic field sensor of claim 1 wherein the linear magnetic field sensor comprises a magnetoresistive element to sense the magnetic field.

4. The magnetic field sensor of claim 1 wherein the voltage-controlled current generating device is operable as a voltage-controlled current sink when the power supply terminal is connected to an external current sensing device.

5. The magnetic field sensor of claim 1 wherein the voltage-controlled current generating device is operable as a voltage-controlled current source when the ground terminal is connected to an external current sensing device.

6. The magnetic field sensor of claim 1 wherein the voltage-controlled current generating device comprises an operational amplifier coupled to a transistor.

7. The magnetic field sensor of claim 6 wherein the transistor comprises a bipolar junction transistor.

8. The magnetic field sensor of claim 6 wherein the transistor comprises a MOSFET.

9. The magnetic field sensor of claim 1 wherein the voltage comprises an analog signal voltage.

10. The magnetic field sensor of claim 1 wherein the linear magnetic field sensor and the interface are implemented in a single integrated circuit.

11. A circuit comprising:

a linear magnetic field sensor comprising an integrated circuit having only two terminals, one a power supply terminal and the other a ground terminal; and

a current sensing device, connected to the linear magnetic field sensor, usable to measure a current that is proportional to a magnetic field sensed by the linear magnetic field sensor.

12. The circuit of claim 11, wherein the current sensing device is connected between the power supply terminal and a power supply.

13. The circuit of claim 12 wherein the linear magnetic field sensor comprises a voltage-controlled current generating device operable as a voltage-controlled current sink.

14. The circuit of claim 11, wherein the current sensing device is connected between the ground terminal and ground.

15. The circuit of claim 14 wherein the linear magnetic field sensor comprises a voltage-controlled current generating device operable as a voltage-controlled current source.

16. The circuit of claim 11 wherein the current sensing device comprises a resistor.

17. The circuit of claim 11 wherein the linear magnetic field sensor comprises a Hall-effect element to sense a magnetic field.

18. The circuit of claim 11 wherein the linear magnetic field sensor comprises a magnetoresistive element to sense a magnetic field.

19. A method comprising:

using a linear magnetic field sensor to produce a current that is proportional to a sensed magnetic field, the linear magnetic field sensor comprising an integrated circuit having only two terminals including a power supply terminal and a ground terminal; and

measuring the current.