Two wire resistive sensor

• US 7,433,267 B2
• Filed: 12/13/2004
• Issued: 10/07/2008
• Est. Priority Date: 12/13/2004
• Status: Expired due to Fees

• Current Assignee: SSI Technologies, LLC (Amphenol Corporation)
• Original Assignee: SSI Technologies, Inc. (Amphenol Corporation)
• Inventors: Murphy, Gregory P., Reimer, Lawrence B.
• Primary Examiner(s): Pihulic; Dan
• Application Number:
  US11/010,921
• Publication Number:
  US 20060125488A1
• Time in Patent Office: 1,394 Days
• Field of Search: 367/135, 367/99, 367/908, 702/166, 702/159, 702/155
• US Class Current: 367/135
• CPC Class Codes: G01D 3/0365 the undesired influence being measured using a separate sensor, which produces an influence related signal
• CPC Class Codes: G01F 25/22 Checking proper indicating of discrete level by floats
• CPC Class Codes: G01F 25/24 Testing proper functioning of electronic circuits
• CPC Class Codes: Y10S 367/908 Material level detection, e.g. liquid level

Abstract

A circuit with two terminals that receive an input current. The circuit includes a sensor, and a controller to generate a modulated signal. The circuit also includes a flyback circuit that receives the modulated signal. The flyback circuit generates a first output voltage based on the modulated signal, shunts or redistributes at least a portion of the input current, and enables the controller to regulate the input current in proportion to the modulated signal.

Claims

1. A circuit having two terminals, the two terminals configured to receive an input current, the circuit comprising:

a sensor;

a controller coupled to the sensor, and configured to generate a modulated signal; and

a flyback circuit coupled to the controller to receive the modulated signal, and operable to generate a first output voltage based on the modulated signal, to shunt at least a portion of the input current, and to enable the controller to regulate the input current in proportion to the modulated signal.

2. The circuit of claim 1, wherein the sensor comprises an ultrasonic sensor.

3. The circuit of claim 1, wherein the flyback circuit comprises at least one of a transistor configured to receive the modulated signal, an inductor configured to generate a portion of the first output voltage supplied to the sensor, and a capacitor configured to generate a second portion of the first output voltage supplied to the sensor.

4. The circuit of claim 1, further comprising a regulator configured to produce a second output voltage based on the first output voltage, and to power the controller with the second output voltage.

5. The circuit of claim 1, wherein the modulated signal comprises a pulse-width-modulated signal.

6. The circuit of claim 1, further comprising a temperature compensating element configured to sense a temperature change and to supply the sensed temperature change to the controller.

7. The circuit of claim 1, further comprising a filtering element configured to filter ripples generated by the flyback circuit.

8. A circuit having two terminals, the circuit comprising:

a means for receiving a current signal;

a means for sensing a condition indicative of a distance;

a means for generating a modulated signal from the condition indicative of the distance; and

a means for shunting at least a portion of the current signal, for enabling the means for generating the modulated signal to regulate the current signal in proportion to the modulated signal.

9. The circuit of claim 8, further comprising a means for regulating the current signal, and for providing the regulated current signal based on the modulated signal.

10. The circuit of claim 8, wherein the means for shunting at least a portion of the current signal comprises a means for switching and for being activated by the modulated signal.

11. The circuit of claim 8, wherein the means for sensing comprises an ultrasonic sensor.

12. The circuit of claim 8, wherein the means for receiving a current signal further comprises two terminals configured to receive the current signal.

13. The circuit of claim 8, wherein the modulated signal comprises a pulse-width-modulated signal.

14. The circuit of claim 8, further comprising a means for supplying a temperature compensating value to the means for generating a modulated signal.

15. The circuit of claim 8, further comprising a means for filtering ripples generated by the means for receiving.

16. A method of emulating a two-wire resistive sensor, the two-wire resistive sensor having two terminals and a processor, the method comprising:

receiving a current signal at the two terminals;

generating a modulated signal at the processor;

shunting at least a portion of the current signal; and

regulating the current signal in proportion to the modulated signal.

17. The method of claim 16, further comprising:

generating a voltage signal in response to the modulated signal; and

providing the voltage signal to a sensor.

18. The method of claim 16, wherein the processor is coupled to a flyback circuit, the method further comprising powering the processor with the flyback circuit based on the modulated signal.

19. The method of claim 16, wherein the processor is coupled to a flyback circuit, the method further comprising powering the processor through a diode.

20. The method of claim 16, wherein the two-wire resistive sensor further comprises an ultrasonic sensor.

21. The method of claim 16, wherein the processor is powered by a first voltage signal, the method further comprising powering a sensor with a second voltage signal that is based on the first voltage signal.

22. The method of claim 16, wherein the modulated signal comprises a pulse-width-modulated signal.

23. The method of claim 16, further comprising:

sensing a temperature; and

supplying a sensed temperature signal to the processor.

24. The method of claim 16, further comprising filtering the voltage signal.

25. A method of emulating a two-wire resistive sensor, the two-wire resistive sensor having two terminals, the two terminals receiving an input current, the method comprising:

sensing a distance;

generating a modulated signal based on the distance;

redistributing at least a portion of the input current based on the modulated signal; and

regulating the input current in proportion to the modulated signal.

26. The method of claim 25, wherein the two-wire resistive sensor further comprises a flyback circuit and a controller, wherein the flyback circuit shunts at least a portion of the input current, and wherein the controller generates the modulated signal, the method further comprising:

generating at the flyback circuit a first voltage signal; and

powering the controller with the first voltage signal.

27. The method of claim 26, wherein generating the first voltage signal comprises activating a transistor with the modulated signal.

28. The method of claim 25, wherein generating the first voltage signal comprises outputting the first voltage signal through a diode.

29. The method of claim 25, wherein sensing the distance comprises sensing with an ultrasonic sensor.

30. The method of claim 25, wherein the modulated signal comprises a pulse-width-modulated signal.

31. The method of claim 25, wherein the distance comprises at least one of a fluid level and a distance between two surfaces.

32. A circuit comprising:

a sensor;

a controller coupled to the sensor, and configured to generate a modulated signal;

a flyback circuit coupled to the controller to receive the modulated signal, and operable to generate a first output voltage based on the modulated signal, and to power the sensor with the first output voltage; and

a regulator configured to produce a second output voltage based on the first output voltage, and to power the controller with the second output voltage.

33. The circuit of claim 32, wherein the sensor comprises an ultrasonic sensor.

34. The circuit of claim 32, wherein the flyback circuit comprises at least one of a transistor configured to receive the modulated signal, an inductor configured to generate a portion of the first output voltage supplied to the sensor, and a capacitor configured to generate a second portion of the first output voltage supplied to the sensor.

35. The circuit of claim 32, further comprising two power inputs configured to receive a gauge power.

36. The circuit of claim 32, wherein the modulated signal comprises a pulse-width-modulated signal.

37. The circuit of claim 32, further comprising a temperature compensating element configured to sense a temperature change and to supply the sensed temperature change to the controller.

38. The circuit of claim 32, further comprising a filtering element configured to filter ripples generated by the flyback circuit.