Two wire resistive sensor
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.
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.