CURRENT SENSOR WITH RESET CIRCUIT

Abstract

A current sensor includes an integrator for providing an output signal, responsive to a detected current, and a reset circuit. The reset circuit, responsive to a control signal, resets the integrator for a time period shorter than an assertion time of the supplied control signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings.

FIG. 1 illustrates a prior art current sensor.

FIG. 2 illustrates a further prior art current sensor.

FIG. 3 illustrates yet another prior art current sensor.

FIG. 4 illustrates a further prior art current sensor.

FIG. 5 a illustrates a coil in close proximity with a large current carrying wire, according to an embodiment of the present invention.

FIG. 5 b illustrates a perspective cut away view of an integrated circuit, including a coupled coil and wire.

FIG. 6 is a cross-sectional view of a first embodiment of an integrated current sensor package.

FIG. 7 is a top view of the first embodiment of the integrated current sensor package.

FIG. 8 is a model (equivalent circuit) of the integrated current sensor illustrated in FIGS. 6 and 7.

FIG. 9 is a cross-sectional view of an alternative embodiment of the integrated current sensor package.

FIG. 10 is a top view of the alternative embodiment of the integrated current sensor package of FIG. 9.

FIG. 11 is a model (equivalent circuit) of the alternative embodiment of the integrated current sensor package illustrated in FIGS. 9 and 10.

FIG. 12 is a schematic diagram of an integrated current sensor.

FIG. 13 is a schematic diagram illustrating an integrated current sensor within a switched power supply circuit.

FIG. 14 is a timing diagram illustrating operation of the switched power supply circuit of FIG. 13.

FIG. 15 illustrates a further circuit for controlling a reset switch of an integrated current sensor.

FIG. 16 is a top view of a further embodiment of the integrated current sensor package.

FIG. 17 is a cross-sectional view of the embodiment of the integrated current sensor package in FIG. 16, along the line 17-17.

FIG. 18 is a further cross-sectional view of the embodiment of the integrated current sensor package in FIG. 16, along the line 18-18.

FIG. 19 is an electrical schematic of a circuit that includes a current sensor implemented in a buck converter application.

FIG. 19 a is a timing diagram illustrating operation of the circuit of FIG. 19.

FIG. 20 is an electrical schematic of a circuit that includes a current sensor with a reset circuit, configured according to one aspect of the present invention.

FIGS. 20 a and 20b are timing diagrams that illustrate operation of the reset circuit of FIG. 20.

FIGS. 21 a illustrates an embodiment in which two coils are used to sense the current instead of one.

FIG. 21 b illustrates another two coil embodiment in which the current carrying wire implemented on the current sensor package is “U” shaped.

FIG. 22 illustrates another view of an embodiment of a dual coil current sensor.

FIG. 23 illustrates of how the dual coils are coupled to the integrator in an exemplary embodiment.

Claims

1. A current sensor for sensing a first current, comprising: an integrator for providing an output signal responsive to a detected current corresponding to the first current; anda reset circuit coupled to receive a control signal and to supply a reset signal to reset the integrator in response to the control signal, the reset signal, when asserted, coupled to cause the integrator to be in a reset state for a time period shorter than an assertion time of the control signal.

2. The current sensor of claim 1, further comprising: a first inductor for receiving the first current; andone or more additional inductors positioned proximate to the first inductor, the one or more additional inductors providing the detected current responsive to the first current.

3. The current sensor of claim 1, wherein the reset circuit is coupled to reset the integrator by causing a capacitor of the integrator to be shorted.

4. The current sensor of claim 1, wherein the integrator is reset when the first current is substantially zero.

5. The current sensor of claim 2, wherein the first inductor is implemented within an integrated circuit package.

6. The current sensor of claim 2, wherein the one or more additional inductors, the integrator and the reset circuit are implemented within an integrated circuit die.

7. The current sensor of claim 2, wherein the integrator is reset when the detected current is substantially zero.

8. The current sensor of claim 1, wherein the reset circuit includes a one-shot circuit and one or more logic gates.

9. The current sensor of claim 8, wherein the one-shot circuit includes an input and an output and the one or more logic gates includes a first input, a second input and an output, and wherein the input of the one-shot circuit and the first input of the one or more logic gates receive the control signal and the output of the one-shot circuit is coupled to the second input of the one or more logic gates, where the output of the one or more logic gates provides the reset signal whose pulse width is the less than a pulse width of the control signal.

10. The current sensor of claim 9, further comprising a switch that resets the integrator responsive to the reset signal.

11. The current sensor of claim 2, wherein the integrator includes an operational amplifier having an inverting input, a non-inverting input and an output and a capacitor having a first terminal and a second terminal, and wherein the inverting input of the operational amplifier is coupled to the one or more additional inductors and the first terminal of the capacitor, and the second terminal of the capacitor is coupled to the output of the operational amplifier, which provides the output signal.

12. The current sensor of claim 1, wherein the integrator and the reset circuit are implemented in an integrated circuit having an input terminal coupled to receive the control signal.

13. A current sensor for sensing a first current, comprising: an integrator for providing an output signal responsive to a detected current corresponding to the first current; andmeans for resetting the integrator in response to a control signal for a time period shorter than a pulse width of the control signal.

14. The current sensor of claim 13, further comprising: a first inductor for receiving the first current; andone or more additional inductors coupled to the integrator and positioned proximate the first inductor, the one or more additional inductors providing the detected current responsive to the first current.

15. A method for sensing a first current comprising: integrating a detected current corresponding to the first current and providing an output indicative thereof from an integrator; andresetting the integrator in response to a control signal supplied to a reset circuit, the integrator being reset for a time period shorter than a pulse width of the control signal.

16. The method of claim 15, further comprising periodically resetting the integrator when the detected current is substantially zero.

17. The method as recited in claim 15 further comprising supplying the control signal to a one shot circuit included in the reset circuit and generating a reset signal to the integrator having a pulse width shorter than the control signal.

18. The method as recited in claim 17 further comprising supplying the control signal as an external signal supplied to an integrated circuit incorporating the one shot circuit and the integrator.

19. The method as recited in claim 15 further comprising: receiving the first current in a first inductor; andproviding the detected current responsive to the first current using one or more additional inductors coupled to the integrator and positioned proximate the first inductor.

20. The method as recited in claim 15 further comprising using the control signal to generate a reset signal to reset the integrator and using the control signal to control flow of the first current.