Switching mode regular for SFP ethernet adaptor

1. A method for regulating voltage on an integrated circuit formed on a substrate to power circuitry on the substrate, comprising the steps of:

providing an unregulated power supply as an input to the integrated circuit connected between a positive node and a reference node on the integrated circuit;

sourcing current in a first current sourcing step through drive circuitry on the substrate from the positive node to an inductor/capacitor reactive circuit external to the integrated circuit, the output of the inductor/capacitor reactive circuit comprising a filtered regulated power supply voltage that is operable to power at least a portion of the circuitry on the substrate;

sourcing current in a second current sourcing step through the drive circuitry on the substrate from the reference node to the inductor/capacitor reactive circuit when the current in the inductor/capacitor reactive circuit is ramping down;

controlling the first and second sourcing steps to alternately source current to the inductor/capacitor reactive circuit from the positive and reference nodes; and

preventing in the step of controlling substantially any current from being drawn through the substrate body during either the first current sourcing step or the second current sourcing step and delivered to the inductor/capacitor reactive circuit during ramp up or ramp down of the current in the inductor/capacitor reactive circuit and during any transition there between.

2. The method of claim 1 wherein the step of preventing comprises the step of controlling controlling the first current sourcing step and the second current sourcing step such that current driven to the inductor/capacitor reactive circuit is substantially continuous during the transition between the first and second current sourcing steps.

3. The method of claim 2 wherein the step of controlling the first current sourcing step and the second current sourcing step is operable to minimize overlap of the first and second current sourcing steps.

4. The method of claim 2 wherein the step of controlling the first current sourcing step and the second current sourcing step is operable to minimize the non-overlap of the first current sourcing step and the second current sourcing step, such that there is no gap between sourcing current to the inductor/capacitor reactive circuit from the positive node or from the reference node.

5. The method of claim 1 , wherein the drive circuitry comprises CMOS switches formed on the surface of the substrate for selectively either sourcing current from the positive node to a pad on the substrate that is connected to the input of the inductor/capacitor reactive circuit in response to a first drive signal or sourcing current from the reference node through the pad to the input of the inductor/capacitor reactive circuit in response to a second drive signal, the first and second drive signals generated in the step of controlling.

6. The method of claim 5 , wherein the CMOS switches are comprised of a p-channel transistor having the source-to-drain path connected between the positive node and the pad and an n-channel transistor having the source-to-drain path connected between the pad and the reference node, the gate of the p-channel transistor driven by the first drive signal and the gate of the n-channel transistor driven by the second drive signal, the first and second drive signals both controlled by the step of controlling during the transition between the first and second current sourcing steps in the step of preventing.

7. The method of claim 6 , wherein the first and second current sourcing steps are not mutually exclusive.

8. The method of claim 6 , wherein the n-channel transistor has associated therewith a PN semiconductor junction that forms a reverse biased diode between the pad and the reference node and the step of preventing prevents the PN junction from becoming forward biased, the substrate body connected to the reference node.

9. The method of claim 6 , wherein:

the first current sourcing step is operable to drive the gate of the p-channel transistor with a first control signal PDRV as the first drive signal;

the second current sourcing step is operable to drive the gate of the n-channel transistor with a second control signal NDRV as the second drive signal; and

controlling with a controller generation of the PDRV and the NDRV signals with a pulse width modulation circuit.

10. The method of claim 6 , wherein the timing of the first and second current sourcing steps and the relationship there between is different for a high to low transition and a low to high transition.

11. The method of claim 1 , wherein the circuitry on the substrate includes digital processing circuitry powered by the filter regulated power supply voltage and analog circuitry contained on the surface of the substrate.

12. The method of claim 11 , wherein the step of preventing is operable to prevent current from flowing proximate to the analog circuitry through the body of the substrate.

13. The method of claim 1 , wherein the step of preventing is based upon the value of the drive signal to the external inductor/capacitor reactive circuit.

14. A method for providing a switching regulator as an integral part of an integrated circuit that is formed on a substrate, the integrated circuit having application circuitry associated therewith, which switching regulator interfaces with reactive elements external to the integrated circuit to provide a filtered regulated voltage for input to a regulated voltage input to the integrated circuit to power at least a portion of the application circuitry on the substrate, comprising the steps of:

providing an unregulated supply as an input to the switching regulator connected between an unregulated power supply node and a ground reference node on the integrated circuit;

controlling during a first current sourcing step a first switch disposed on the substrate to selectively source current from the unregulated power supply node to the reactive elements;

controlling during a second current sourcing step a second switch disposed on the substrate to selectively source current from the ground reference node to the reactive elements; and

the steps of controlling the first and second switches timed such that substantially any current being sourced through the substrate body is prevented as current is delivered to the reactive elements during ramp up or ramp down of the voltage on the reactive elements.

15. The method of claim 14 wherein the steps of controlling the first and second switches are timed such that current sourced to the reactive elements is substantially continuous and with the current sourced by the first and second switches alternating.

16. The method of claim 15 wherein the steps of controlling the first and second switches is timed so as to minimize overlap of current sourced by the first and second switches.

17. The method of claim 15 wherein the steps of controlling the first and second switches is timed so as to minimize the non-overlap of current sourced by the first and second switches, such that there is no gap between driving current to the reactive elements from the unregulated power supply node or from the ground reference node.

18. The method of claim 14 , wherein the first and second switches comprise a CMOS pair of switches formed on the surface of the substrate for selectively either sourcing current from the unregulated power supply node to a pad on the substrate that is connected to the reactive elements or sourcing current from the ground reference node through the pad to the reactive elements.

19. The method of claim 18 , wherein the pair of CMOS switches is comprised of a p-channel transistor as the first switch having the source-to-drain path connected between the unregulated power supply and the pad and an n-channel transistor as the second switch having the source-to-drain path connected between the pad and the ground reference.

20. The method of claim 19 , wherein the n-channel transistor has associated therewith a PN semiconductor junction that forms a reverse biased diode between the pad and the ground reference node to which the body of the substrate is connected and the steps of controlling the first and second switches is timed so as to prevent the PN junction from becoming forward biased.

21. The method of claim 14 , wherein the application circuitry on the substrate includes digital processing circuitry powered by the filtered regulated power supply voltage and analog circuitry contained on the surface of the substrate.

22. The method of claim 21 , wherein the steps of controlling the first and second switches is timed so as to prevent current from flowing proximate to the analog circuitry through the body of the substrate, the body of the substrate connected to the ground reference node.

23. A method for providing a switching regulator as an integral part of an integrated circuit that is formed on a substrate, the integrated circuit having application circuitry associated therewith which includes digital processing circuitry and analog circuitry contained on the surface of the substrate, which switching regulator interfaces through a pad with reactive elements external to the integrated circuit to provide a filtered regulated voltage for input to a regulated voltage input to the integrated circuit to power at least the digital processing circuitry portion of the application circuitry on the substrate, comprising the steps of:

providing an unregulated supply as an input to the switching regulator connected between an unregulated power supply node and a ground reference node on the integrated circuit, the substrate body connected to the ground reference node;

the pad having associated therewith a PN substrate diode junction to the ground reference node that is reverse biased with positive voltages;

controlling during a first current sourcing step a first switch disposed on the substrate to selectively source current from the unregulated power supply node to the reactive elements;

controlling during a second current sourcing step a second switch disposed on the substrate to selectively source current from the ground reference node to the reactive elements; and

the steps of controlling the first and second switches timed such that substantially any current being sourced through the substrate body due to forward biasing of the PN substrate diode junction is prevented as current is sourced to the reactive elements during ramp up or ramp down of the voltage on the reactive elements.

24. The method of claim 23 wherein the steps of controlling the first and second switches are timed such that current sourced to the reactive elements is substantially continuous and with the current sourced by the first and second switches alternating.

25. The method of claim 24 wherein the steps of controlling the first and second switches is timed so as to minimize overlap of current sourced by the first and second switches.

26. The method of claim 25 wherein the steps of controlling the first and second switches is timed so as to minimize the non-overlap of current sourced by the first and second switches, such that there is substantially no gap between sourcing current to the reactive elements from the unregulated power supply node or from the ground reference node.

27. The method of claim 23 , wherein the first and second switches comprise a CMOS pair of switches formed on the surface of the substrate for selectively either sourcing current from the unregulated power supply node to a pad on the substrate that is connected to the reactive elements or sourcing current from the ground reference node through the pad to the reactive elements.

28. The method of claim 27 , wherein the pair of CMOS switches is comprised of a p-channel transistor as the first switch having the source-to-drain path connected between the unregulated power supply and the pad and an n-channel transistor as the second switch having the source-to-drain path connected between the pad and the ground reference, wherein the n-channel transistor has associated therewith a PN semiconductor junction that forms the PN substrate diode junction.

29. The method of claim 23 , wherein the steps of controlling the first and second switches is timed so as to prevent current from flowing proximate to the analog circuitry from the PN substrate diode junction through the body of the substrate.

30. A regulating circuit for regulating voltage on an integrated circuit formed on a substrate to power circuitry on the substrate, comprising:

an unregulated power supply provided as an input to the integrated circuit connected between a positive node and a reference node on the integrated circuit;

a first current source for sourcing current through drive circuitry on the substrate from said positive node to an inductor/capacitor reactive circuit external to the integrated circuit, the output of said inductor/capacitor reactive circuit comprising a filtered regulated power supply voltage that is operable to power at least a portion of the circuitry on the substrate;

a second current source for sourcing current through said drive circuitry on the substrate from said reference node to said inductor/capacitor reactive circuit when the current in said inductor/capacitor reactive circuit is ramping down;

a controller for controlling said first and second current sources to alternately source current to said inductor/capacitor reactive circuit from said positive and reference nodes; and

said controller preventing substantially any current from being drawn through the substrate body by either said first current source or said second current source and delivered to said inductor/capacitor reactive circuit during ramp up or ramp down of the current in said inductor/capacitor reactive circuit and during any transition there between.

31. The regulating circuit of claim 30 wherein said controller is operable to control said first current source and said second current source such that current driven to said inductor/capacitor reactive circuit is substantially continuous during the transition between current being sourced by said first current source and current being sourced by said second current source.

32. The regulating circuit of claim 31 wherein said controller is operable to minimize overlap of current being sourced by said first current source and current being sourced by said second current source.

33. The regulating circuit of claim 32 wherein said controller is operable to minimize the non-overlap of current being sourced by said first current source and current being sourced by said second current source, such that there is no gap between sourcing current to said inductor/capacitor reactive circuit from said positive node or from said reference node.

34. The regulating circuit of claim 30 , wherein said drive circuitry comprises CMOS switches formed on the surface of the substrate for selectively either sourcing current from said positive node to a pad on the substrate that is connected to the input of said inductor/capacitor reactive circuit in response to a first drive signal or sourcing current from said reference node through said pad to the input of said inductor/capacitor reactive circuit in response to a second drive signal, said first and second drive signals generated by said controller.

35. The regulating circuit of claim 34 , wherein said CMOS switches are comprised of a p-channel transistor that provides the functionality of said first current source and having the source-to-drain path thereof connected between said positive node and said pad and an n-channel transistor providing the functionality of said second current source and having the source-to-drain path thereof connected between said pad and said reference node, the gate of said p-channel transistor driven by said first drive signal and the gate of said n-channel transistor driven by said second drive signal, said first and second drive signals both controlled by said controller during the transition between current being sourced by said first current source and current being sourced by said second current source.

36. The regulating circuit of claim 35 , wherein the operation of said first and second current sources steps are not mutually exclusive.

37. The regulating circuit of claim 35 , wherein said n-channel transistor has associated therewith a PN semiconductor junction that forms a reverse biased diode between said pad and said reference node and said controller prevents the PN junction from becoming forward biased, the substrate body connected to said reference node.

38. The regulating circuit of claim 35 , wherein:

said controller is operable to drive the gate of said p-channel transistor with a first control signal PDRV as said first drive signal;

said controller is operable to drive the gate of said n-channel transistor with a second control signal NDRV as said second drive signal; and

said controller is operable to control generation of said PDRV and said NDRV signals with a pulse width modulation circuit.

39. The regulating circuit of claim 35 , wherein the timing of said first and second current sources and the relationship there between is different for a high to low transition and a low to high transition.

40. The regulating circuit of claim 30 , wherein the circuitry on the substrate includes digital processing circuitry powered by the filter regulated power supply voltage and analog circuitry contained on the surface of the substrate.

41. The regulating circuit of claim 40 , wherein said controller is operable to prevent current from flowing proximate to the analog circuitry through the body of the substrate.

42. The regulating circuit of claim 30 , wherein said controller receives as an input the value of the drive signal to said external inductor/capacitor reactive circuit, and bases the control operation in part on such value.

43. A switching regulator formed as an integral part of an integrated circuit on a substrate, the integrated circuit having application circuitry associated therewith, which switching regulator interfaces with reactive elements external to the integrated circuit to provide a filtered regulated voltage for input to a regulated voltage input to the integrated circuit to power at least a portion of the application circuitry on the substrate, comprising:

an unregulated supply provided as an input to the switching regulator connected between an unregulated power supply node and a ground reference node on the integrated circuit;

a controller for controlling during a first current sourcing operation a first switch disposed on the substrate to selectively source current from the unregulated power supply node to the reactive elements;

said controller controlling during a second current sourcing operation a second switch disposed on the substrate to selectively source current from said ground reference node to the reactive elements; and

said controller timing the operations of sourcing such that substantially any current being sourced through the substrate body is prevented as current is delivered to the reactive elements during ramp up or ramp down of the voltage on the reactive elements.

44. The switching regulator of claim 43 wherein the operation of controlling said first and second switches is timed such that current sourced to the reactive elements is substantially continuous and with the current sourced by said first and second switches alternating.

45. The switching regulator of claim 44 wherein the operation of controlling said first and second switches is timed so as to minimize overlap of current sourced by said first and second switches.

46. The switching regulator of claim 44 wherein the operation of controlling said first and second switches by said controller is timed so as to minimize the non-overlap of current sourced by said first and second switches, such that there is no gap between driving current to the reactive elements from said unregulated power supply node or from said ground reference node.

47. Said switching regulator of claim 43 , wherein said first and second switches comprise a CMOS pair of switches formed on the surface of the substrate for selectively either sourcing current from said unregulated power supply node to a pad on the substrate that is connected to the reactive elements or sourcing current from said ground reference node through said pad to the reactive elements.

48. Said switching regulator of claim 47 , wherein said pair of CMOS switches is comprised of a p-channel transistor as said first switch having the source-to-drain path connected between said unregulated power supply and said pad and an n-channel transistor as said second switch having the source-to-drain path connected between said pad and said ground reference.

49. Said switching regulator of claim 48 , wherein said n-channel transistor has associated therewith a PN semiconductor junction that forms a reverse biased diode between said pad and said ground reference node to which the body of the substrate is connected and the operation of controlling said first and second switches is timed so as to prevent the PN junction from becoming forward biased.

50. Said switching regulator of claim 43 , wherein the application circuitry on the substrate includes digital processing circuitry powered by the filtered regulated power supply voltage and analog circuitry contained on the surface of the substrate.

51. Said switching regulator of claim 50 , wherein the operation of controlling said first and second switches by said controller is timed so as to prevent current from flowing proximate to the analog circuitry through the body of the substrate, the body of the substrate connected to said ground reference node.

52. A switching regulator formed as an integral part of an integrated circuit that on a substrate, the integrated circuit having application circuitry associated therewith which includes digital processing circuitry and analog circuitry contained on the surface of the substrate, which switching regulator interfaces through a pad with reactive elements external to the integrated circuit to provide a filtered regulated voltage for input to a regulated voltage input to the integrated circuit to power at least the digital processing circuitry portion of the application circuitry on the substrate, comprising the steps of:

an unregulated supply provided as an input to the switching regulator connected between an unregulated power supply node and a ground reference node on the integrated circuit, the substrate body connected to said ground reference node;

the pad having associated therewith a PN substrate diode junction to said ground reference node that is reverse biased with positive voltages;

a controller for controlling during a first current sourcing operation a first switch disposed on the substrate to selectively source current from said unregulated power supply node to the reactive elements;

said controller for controlling during a second current sourcing operation a second switch disposed on the substrate to selectively source current from said ground reference node to the reactive elements; and

said controller controlling the timing of the operation of said first and second switches such that substantially any current being sourced through the substrate body due to forward biasing of the PN substrate diode junction is prevented as current is sourced to the reactive elements during ramp up or ramp down of the voltage on the reactive elements.

53. The switching regulator of claim 52 wherein the operation of controlling said first and second switches is timed such that current sourced to the reactive elements is substantially continuous and with the current sourced by said first and second switches alternating.

54. The switching regulator of claim 53 wherein the operation of controlling said first and second switches is timed so as to minimize overlap of current sourced by said first and second switches.

55. The switching regulator of claim 54 wherein the operation of controlling said first and second switches is timed so as to minimize the non-overlap of current sourced by said first and second switches, such that there is substantially no gap between sourcing current to the reactive elements from said unregulated power supply node or from said ground reference node.

56. The switching regulator of claim 53 , wherein said first and second switches comprise a CMOS pair of switches formed on the surface of the substrate for selectively either sourcing current from said unregulated power supply node to a pad on the substrate that is connected to the reactive elements or sourcing current from said ground reference node through said pad to the reactive elements.

57. The switching regulator of claim 56 , wherein said pair of CMOS switches is comprised of a p-channel transistor as said first switch having the source-to-drain path connected between the unregulated power supply and said pad and an n-channel transistor as said second switch having the source-to-drain path connected between said pad and said ground reference, wherein said n-channel transistor has associated therewith a PN semiconductor junction that forms the PN substrate diode junction.

58. The switching regulator of claim 53 , wherein the operation of controlling said first and second switches is timed so as to prevent current from flowing proximate to the analog circuitry from the PN substrate diode junction through the body of the substrate.