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A power converter capable of providing a range of DC voltages to an external device and a method of providing a range of DC power are provided. The power converter comprises a supply circuit for receiving a request for DC power and for providing the requested DC power. The supply circuit comprises

A power converter capable of providing a range of DC voltages to an external device and a method of providing a range of DC power are provided. The power converter comprises a supply circuit for receiving a request for DC power and for providing the requested DC power. The supply circuit comprises a detection circuit for sensing a connection to an external device, a source controller circuit for determining a DC output power required by the external device, and a converter circuit for generating the required DC output power. The external device comprises a device controller circuit for communicating the request for DC power. A first conductor provides a path for the device to communicate the required DC power to the power converter and for the power converter to supply the required DC power. A second conductor provides a common reference for conducting return current to the power converter.

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What is claimed is: 1. A power converter capable of providing a range of DC power, comprising: a supply circuit for receiving a request for DC power from at least one external device and for providing the requested DC power to the at least one external device, wherein the external device comprises:

What is claimed is: 1. A power converter capable of providing a range of DC power, comprising: a supply circuit for receiving a request for DC power from at least one external device and for providing the requested DC power to the at least one external device, wherein the external device comprises: a device controller circuit for communicating the requested DC powers using a communications protocol selected from a plurality of communications protocols including a simple protocol and a complex protocol, wherein the simple protocol is identified when a capacitive load of the external device is greater than a threshold capacitive value and the complex protocol is identified when the capacitive load is less than the threshold capacitive value; and first and second conductors for connecting the at least one external device to the power converter, wherein the first conductor provides a path for the at least one external device to communicate the requested DC output power to the power converter and for the power converter to supply the requested DC output voltage to the at least one external device, and wherein the second conductor provides a common reference for conducting return current to the power converter. 2. The power converter of claim 1, further comprising: an input circuit for receiving an input voltage and generating a DC input voltage. 3. The power converter of claim 2, wherein the input circuit receives an AC voltage. 4. The power converter of claim 2, wherein the input circuit receives a DC voltage. 5. The power converter of claim 2, wherein the supply circuit comprises: a detection circuit for sensing a connection to the at least one external device; a source controller circuit for determining the requested DC output power; and a converter circuit for generating the requested DC output power from the generated DC input voltage after the DC output power has been determined. 6. The power converter of claim 5, wherein the converter circuit is configurable as a current source. 7. The power converter of claim 2, wherein the supply circuit comprises: a plurality of detection circuits for sensing connections to a plurality of external devices; a single source controller circuit for determining a plurality of DC output powers required by the plurality of external devices; and a plurality of converter circuits for generating the plurality of required DC output powers from the generated DC input voltage, wherein the single source controller monitors the required DC output powers from the plurality of external devices. 8. The power converter of claim 7, wherein the single source controller refuses the request for DC power from the at least one external device when the requested DC output power exceeds an available power supply of the power converter. 9. The power converter of claim 2, wherein the DC input voltage is received from a second power converter, the power converter further comprising: a universal device controller circuit for communicating a request for DC input power over a bridge connection to the second power converter, wherein the DC input power is also supplied over the bridge connection. 10. The power converter of claim 1 wherein the power converter is implemented in a semiconductor device. 11. A method of providing DC power to an external device connected to a power source by a first conductor and a second conductor, the method comprising: receiving a request for DC output power from the external device over the first conductor; transmitting the requested DC output power to the external device over the first conductor, wherein the second conductor provides a common reference for conducting return current to the power source; and supplying a constant current to the external device such that a voltage level on the first conductor ramps in a linear fashion. 12. The method of claim 11, further comprising: generating a DC input voltage from a received input voltage; detecting a connection between the external device and the power source, wherein the power source is a power converter; determining the DC output power required by the external device; generating the required DC output power from the DC input voltage; and supplying the required DC output power to the external device. 13. The method of claim 12, wherein detecting the connection between the external device and the power converter comprises: sampling a voltage level at a first conductor connecting the external device to the power converter, wherein the connection is detected when the voltage level drops below a threshold voltage value. 14. The method of claim 11, further comprising measuring a capacitive load on the first conductor to identify a communications protocol selected from a plurality of communications protocols including a simple protocol and a complex protocol, prior to transmitting the requested DC output power. 15. The method of claim 14, wherein the simple protocol is identified when the capacitive load is greater than a threshold capacitive value and the complex protocol is identified when the capacitive load is less than the threshold capacitive value. 16. The method of claim 15 wherein the threshold capacitive value is approximately 0.1 microfarads. 17. The method of claim 14 wherein, if the external device is determined to be using the simple protocol, the method further comprises: determining a maximum average current required by the external device; and repeatedly sampling a voltage level at the first conductor until a steady value of the sampled voltage level is measured to determine the requested DC output power. 18. A method of providing DC power to an external device connected to a power source by a first conductor and a second conductor, the method comprising: receiving a request for DC output power from the external device over the first conductor; and transmitting the requested DC output power to the external device over the first conductor, wherein the second conductor provides a common reference for conducting return current to the power source; and measuring a capacitive load on the first conductor to identify a communications protocol selected from a plurality of communications protocols including a simple protocol and a complex protocol, prior to transmitting the requested DC output power wherein, if the external device is determined to be using the complex protocol, the method further comprises: receiving a communications packet formed by the external device prior to transmitting the DC output power, the packet indicating select electrical parameters including the requested DC output power. 19. The method of claim 18, wherein the electrical parameters of the DC output power comprise: a DC output voltage; a maximum average current; a maximum peak current; and a slew rate of DC output voltage turn-on ramp. 20. The method of claim 18, wherein the communications packet further comprises a parameter for signaling that the external device includes a battery requiring a recharge operation. 21. The method of claim 20, wherein generating and supplying the requested DC output power in the battery recharge operation comprises: configuring a converter circuit into a current source; generating a current, the current value defined by the communications packet; charging the battery with the generated current until the voltage level at the first conductor reaches the DC voltage value defined by the communications packet; and entering a final charging phase. 22. The method of claim 21, wherein the final charging phase is a constant voltage phase comprising: configuring the converter circuit as a voltage source; generating a DC voltage, the voltage value defined by the communications packet; and charging the battery with the generated DC voltage until the battery is fully charged or until the battery is disconnected. 23. A method comprising: receiving a request for DC power from at least one external device including a rechargeable battery, the external device connected to a DC power source by a conductor; identifying a device voltage level and a device current level for the external device; configuring a converter circuit as a current source; generating a current corresponding to the device capacity level; applying the generated current for a predetermined time to the conductor; disabling the converter circuit configured as a current source; and charging the battery until a voltage level on the conductor reaches the device voltage level or until the battery is disconnected. 24. A system for providing a range of DC power to an external device connected to a power source by a first conductive means and a second conductive means, comprising: means for communicating a request for DC power from the external device over the first conductive means, wherein the means for communicating a request for DC power comprises a communications protocol selected from a plurality of communications protocols including a simple protocol and a complex protocol, and wherein the simple protocol is identified when the capacitive load is greater than a threshold capacitive value and the complex protocol is identified when the capacitive load is less than the threshold capacitive value; and means for providing the requested DC power to the external device over the first conductive means, wherein the second conductive means provides a common reference for conducting return current from the external device to the power source. 25. The system of claim 24, further comprising: means for receiving an input voltage and generating a DC input voltage; means for detecting a connection to the at least one external device; means for determining a DC output voltage required by the at least one external device; and means for generating the required DC output voltage from the generated DC input voltage. 26. The system of claim 24, wherein the means for communicating a request for DC power for the simple protocol comprises: means for establishing a DC output voltage required by the at least one external device; and means for establishing the maximum average current required by the at least one external device. 27. The system of claim 24, wherein the means for communicating a request for DC power for the complex protocol comprises: means for forming communications packets indicating select electrical parameters of the requested DC power. 28. The system of claim 27, wherein the electrical parameters of the requested DC power comprise: a DC output voltage; a maximum average current; a maximum peak current; a slew rate of DC output voltage turn-on ramp; a battery charge current; and a battery fast charge time. 29. The power converter of claim 1, wherein the device controller circuit comprises: a first circuit for establishing the required DC output voltage; and a second circuit for establishing a maximum average current of the at least one external device. 30. The power converter of claim 29, wherein the first circuit comprises a zener diode and a first transistor connected in series between the first and second conductors. 31. The power converter of claim 29, wherein the first circuit comprises a resistor connected between the first and second conductors. 32. The power converter of claim 29, wherein the second circuit comprises a capacitor connected between the first and second conductors. 33. The power converter of claim 29, wherein the device controller circuit further comprises a switching circuit for detecting the DC output power supplied by the power converter and providing the supplied DC output power to the at least one external device. 34. The power converter of claim 29, wherein the device controller circuit further comprises: a loading circuit coupled to the first and second conductors for providing a disconnect signal to the power converter. 35. The power converter of claim 34, wherein the loading circuit comprises a resistor and a transistor connected in series between the first and second conductors. 36. The power converter of claim 1, wherein the device controller circuit comprises: a first circuit for signaling the presence of the DC-powered device to the power converter; a communications circuit for forming a communications packet indicating select electrical parameters of the required DC output power; a switching circuit for detecting the DC output power supplied by the power converter and providing the supplied DC output power to the at least one external device; and a loading circuit coupled to the first and second conductors for providing a disconnect signal to the power converter. 37. The power converter of claim 36, further comprising: a power supply circuit having an input coupled to the first conductor and an output coupled to the device controller circuit, wherein the output remains steady for short periods of time when power to the input is removed. 38. The method of claim 23, wherein the device voltage level and the device capacity level are included in a communications packet received from the external device. 39. The method of claim 38, wherein the communications packet further comprises a parameter for signaling that the external device includes the rechargeable battery. 40. The power converter of claim 1, wherein the capacitive load is measured on the first conductor. 41. The power converter of claim 1, wherein the power converter is configured to provide an initial DC power supply to the at least one external device, the initial DC power supply sufficient to allow the at least one external device to communicate with the power converter, and wherein the requested DC power is greater than the initial DC power supply.