DC POWER ADAPTER SYSTEM

Abstract: A secondary adapter for receiving a DC power signal and providing an output power signal as an input to an AC power adapter is disclosed. The AC power adapter may then provide a DC power signal to meet the input power from an AC power source, the secondary adapter converts a DC power source to provide an input power signal which is sufficient to power the AC power adpater converts a DC power source to provide an input power signal which is sufficient to power the AC power adapter. The secondary adapter enables the AC power adapter to provide power to the electronic appliance from either an AC power source of a DC power source.

Description: DC POWER ADAPTER SYSTEM NOTICE OF COPYRIGHTS A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the United States Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever. RELATED APPLICATIONS This application is a continuation-in-part application of utility application 09/310,461 filed on May 12, 1999, which is a continuation-in-part application of utility application 09/148,811 filed on September 4, 1998 and a continuation-in-part of utility application 09/213,018, now U.S. Patent No. 5,949,213 issued on September 7, 1999, which are continuations-in-part of utility application 08/994,905, now U.S. Patent No. 5,838,554, which is a continuation-in-part of utility application 08/767,307 filed December 16, 1996, which is a continuation-in-part application of utility application 08/567,369 filed December 4, 1995, now U.S. Patent No.5,636,110 issued June 3, 1997, and claims priority of provisional application Serial No. 60/002,488 filed August 17, 1995, and is also a continuation-in-part application of utility application Serial No. 08/233,121 filed April 26, 1994, now U.S. Patent No. 5,479,331 issued December 26, 1995. BACKGROUND Field of the Invention: This invention relates to power supplies and in particular relates to power supplies for use with a variety of different devices . Related Art: Prior art power supplies include a variety of techniques, particularly those used for powering microelectronics such as the class of computers commonly known as "notebook" computers such as the Powerbook Series available from Apple Computer of Cupertino California and the Thinkpad Series available from International Business Machines (IBM) of Armonk, New York. More recently, even smaller personal computers referred to as "sub- notebooks" have also been developed by various companies such as Hewlett-Packard's Omnibook. The goal of these notebooks and sub-notebooks designs is to reduce the size and weight of the product. Currently, notebooks typically weigh about six pounds and sub- notebooks weigh slightly less than four pounds. Many of these notebook and sub-notebook computers have a battery that must be recharged. Also, typically the computers are designed to be operated from external power sources such as line current and the electrical power system of automobiles. To power these computers, the manufacturer typically provides an external power source. The external power source may be a switching power supply that may weigh close to a pound and may be about eight inches long, four inches wide and about four inches high. Smaller power supplies do exist but frequently they lack sufficient power to charge new batteries such as nickel hydride batteries. Such external power supplies therefore contribute substantial additional weight that the user of the computer must carry with him or her to permit battery charging and/or operation from an electrical socket. Further, the external power supply is bulky and may not be readily carried in typical cases for such notebook and sub-notebook computers. In addition, conventional power supplies often have difficulty providing the necessary power curve to recharge batteries that have been thoroughly discharged. Also, a power supply is needed for each peripheral device, such as a printer, drive or the like. Thus, a user needs multiple power supplies. While it has long been known to be desirable to reduce the size and weight of the power supply, this has not been readily accomplished. Many of the components such as the transformer core are bulky and have significant weight. Further, such power supplies may need to be able to provide DC power of up to seventy-five watts, thereby generating substantial heat. Due to the inherent inefficiencies of power supplies, this results in substantial heat being generated within the power supply. Reduction of the volume, weight and heat are all critical considerations for a power supply in this type of application and cannot be readily accomplished. In particular, it is believed to be desirable to have a package as thin as possible and designed to fit within a standard pocket on a shirt or a standard calculator pocket on a brief case. In addition, conventional power supplies are device specific and each device requires its own power supply. Therefore, users need multiple power supplies, which consumes space and increases unnecessary weight. Cellular telephones are also extensive users of batteries. Typically, cellular telephone battery chargers have been bulky and are not readily transportable. Moreover, cellular telephone battery chargers often take several hours, or more, to charge a cellular telephone battery. Summary An embodiment of the present invention is directed to a system for providing DC power to an electronic appliance, a primary power adapter includes a power input terminal adapted for receiving an AC voltage within a set range and a power output terminal for providing a DC signal to meet an input power requirement of the electronic appliance. A secondary power adapter includes a DC power input terminal adapted for receiving a power signal from a DC power source at a set voltage range, and a power output terminal adapted to couple to the input power terminal of the primary power adapter to apply an intermediate power signal to the power input terminal of the primary power adapter within the set range. The intermediate power signal applied to the input power terminal of the primary adapter may cause the primary adapter to provide a power signal to meet the input power requirement of the portable electronic appliance. Other features and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, various features of embodiments of the invention. Brief Description of the Figures A detailed description of embodiments of the invention will be made with reference to the accompanying drawings, wherein like numerals designate corresponding parts in the several figures. Figure 1 is a block diagram of a first embodiment of the disclosed invention. Figure 2 is a sectional view of the E core for use in the embodiments of Figure 1. Figures 3 A and B are a detailed circuit schematic of the embodiment of Figure 1. Figure 4 is a top planar view of a printed circuit board containing the circuit of Figure 3. Figure 5 A is a top planar view of a case or housing for an additional embodiment of the for an invention where the case houses the other components. Figure 5B is a partial cross-section of the louvers and openings of the case top as shown in Figure 5 A. Figure 5C is a partial cross-section of another embodiment of the louvers formed from raised ridges and depressions on the case top. Figure 6 is a top planar view of one of two heat sinks for the additional embodiment of the invention that sandwich a printed circuit board containing the circuitry for the additional embodiment. Figures 7 A and 7B are a schematic diagram of the additional embodiment of the invention. Figure 8 is a timing diagram for the circuit shown in Figure 7. Figure 9 is a block diagram of the Ul integrated circuit shown in Figure 7. Figures 10A and B are timing diagrams for the block diagram shown in Figure 9. Figure 11 is a power versus output current curve and an output voltage versus current curve of a power supply in accordance with an embodiment of the present invention. Figures 12A-12C are a top plan view and two side plan views of a transformer core in accordance with another embodiment of the present invention. Figures 13A-13C are a top plan view and two side plan views of a transformer cap for use with the transformer core shown in Figures 12A-12C. Figure 14 is a top plan view of a printed circuit board layer, without winding patterns, to be coupled with the transformer core shown in Figures 12A-12C. Figure 15 is a top plan view of another printed circuit board layer showing a secondary winding pattern to be coupled with to the transformer core shown in Figures 12A-12C. Figure 16 is a top plan view of another printed circuit board layer showing a primary winding pattern to be coupled with the transformer core shown in Figures 12A-12C. Figures 17A-17C are a top plan view and two side plan views of a transformer core in accordance with an alternative embodiment of the present invention. Figures 18A-18C are a top plan view and two side plan views of a transformer cap for use with the transformer core shown in Figures 17A-17C. Figure 19 is a top plan view of a printed circuit board layer with a secondary winding pattern to be coupled with the transformer core shown in Figures 17A- 17C. Figure 20 is a top plan view of another printed circuit board layer showing primary winding patterns to be coupled with the transformer core shown in Figures 17A-17C. Figure 21 is a top plan view of another printed circuit board layer showing additional primary winding patterns to be coupled with the transformer core shown in Figures 17A-17C. Figure 22 is a top plan view of another printed circuit board layer showing a another secondary winding pattern to be coupled with the transformer core shown in Figures 17A-17C. Figure 23 is a schematic of a control circuit in accordance with an embodiment of the present invention. Figure 24 is a schematic of a programing circuit in accordance with an embodiment of the present invention that is used to digitally program the power supply to produce between 0 and 16 volts. Figure 25 is a schematic of another programing circuit in accordance with an embodiment of the present invention that is used to digitally program the power supply to produce between 16 and 18 volts. Figure 26 is an end view of a connector that mates with the small form factor power supply and is useable to program the small form factor power supply. Figures 27(a) - 34(c) show various cables with connectors in accordance with embodiments of the present invention that program the small form factor power supply for supplying power to different devices. Figures 35(a)-40(c) show various connector adapters four use with the cable shown above in Figures 34(a)-34(c). Figures 41(a) and 41(b) illustrate a block diagram and a schematic of an interface for providing power to more than one device at a time. Figure 42 shows a top and rear perspective view of a small form factor power supply for use with portable telephone equipment. Figure 43 shows a top and front perspective view of the small form factor power supply shown in Figure 42. Figure 44 shows a bottom and front perspective view of the small form factor power supply shown in Figure 42. Figure 45 shows a side perspective view of the small form factor power supply shown in Figures 42-44 connected to a cellular telephone battery and telephone. Figure 46 shows a top front perspective view of the small form factor power supply shown in Figures 42-44 connected to a cellular telephone battery and telephone. Figure 47 shows a top and front perspective view of a small form factor power supply adapter connector for use with portable telephone equipment. Figure 48 shows a top perspective view of the adapter connector shown in Figure 47. Figure 49 shows a bottom perspective view of the adapter connector shown in Figure 47 Figure 50 shows a right side view of the adapter connector shown in Figure 47. Figure 51 shows a schematic diagram of an alternative embodiment of a power supply which receives input power from a DC source. Figure 52 shows an alternative embodiment of a form factor power supply including a connector for coupling to a detachable plug. Figure 53 shows an embodiment of a secondary adapter for receiving a DC power signal which is adapted for coupling to the form factor power supply shown in Figure 52. Figures 54A, 54B and 54C show three views of the secondary adapter according the embodiment of the Figure 53. Figure 55 shows circuitry for converting a DC input signal in an embodiment of the secondary adapter shown in Figure 52. Figure 56 shows circuitry for converting a DC input signal in an alternative embodiment of the secondary adapter shown in Figure 52. Detailed Description Embodiments of the present invention are directed to a secondary power adapter for receiving power from a DC power source and providing an output power signal which is suitable for powering a power supply adapted for receiving an AC power signal. Accordingly, the secondary adapter enables the use of the power supply adapted for receiving the AC power signal for powering an electronic appliance from either an AC power source or a DC power source. Figure 1 shows a block diagram of the power supply according to an embodiment of the present invention. All components on the left side of a magnetic core 20 are part of the primary portion 100 and all portions on the right hand side are part of the secondary portion 200 of the power supply. The primary portion 100 includes a primary rectifier and input circuit 110, a first primary and drive circuit 120, a second primary and drive circuit 130, a primary feedback circuit 140 and a controller 150. The secondary portion 200 includes a secondary output circuit 210 and a secondary feedback circuit 240. The function of the primary rectifier and input circuit 110 is to couple the embodiment 10 to the line voltage (for example 110 volt, 60 Hz), to rectify that voltage and provide DC power for the remainder of the primary portion 100 and a ground path for the primary circuits 120 and 130. The controller 150, which may be a Unitrode 3875 provides two square wave driver signals 152 and 154 having alterable phases to the first and the second primary circuits 120 and 130. The first and second primary circuits are resonant circuits that are resonant at about the frequency of the driver signals and include coils that are coupled to the core 20, which may be a planar or low profile "E" type core, which may be any low loss material, as is shown in a sectional view in Figure 2. Hence, the driver signals are magnetically coupled to the core 20 by first and second primary coils contained within the circuits 120, 130. The coil 212 in the secondary circuit 210 is preferably positioned relative to the coils of the two primary cores so that the coil in the secondary circuit is at a summing point of the magnetic flux from the primary circuit coils. If a planar or low profile "E" type core as shown in Figure 2 is used, the coil 212 for the secondary circuit 210 is positioned about the central leg 22. The coil for the feedback circuits 140 is positioned on one of the outer legs 24, 26. As a result, the magnetic flux from the two primary coils of the primary circuits 120, 130 are summed at the position where the secondary coil 212 for the secondary circuit 210 is positioned. (This positioning of the coils is shown in Figure 1 by using the double line to indicate the central leg 22 and a single line to represent the outer legs 24, 26). The amplitude of the DC voltage and current produced by the secondary circuit 210 are monitored by the secondary feedback circuit 230. The primary feedback circuit 140 and the secondary feedback circuit 230 are magnetically coupled by coils positioned on another core 23 to provide a feedback signal to the controller 150. In response to the feedback signal, the controller alters the relative phase between the two driver signals 152 and 154 to obtain the desired magnitude of the voltage and current. Since the secondary coil 212 is located at a summing point on the core of the flux from the two primary coils, as the phase between the driving signals 152 and 154 to the two primary coils alters, the magnitude of the current and voltage induced in the secondary coil will vary. This will permit control of the secondary circuit 210 output voltage and current, thereby providing a readily controlled output voltage. Figure 3 shows a more detailed schematic of an embodiment of the invention. A standard AC plug may be coupled to input nodes 111, 112 to a first filter coil LI that is coupled to a full wave rectifier bridge 113, which may be a MDA106G. Filtering capacitors Cl, C2, C7, C8 are also coupled to the bridge 113 and one side of the bridge is coupled to AC ground. The other side of the bridge is coupled to the primary coils 122 and 132 of the first and second primary circuits 120, 130 respectively. The other terminal of the primary coils 122, 132 are coupled to the remainder of the primary circuits 120 and 130. Each of these primary circuits 120, 130 also comprise a drive field effect 124, 134, which may be a MTP6N60 and a capacitor 126, 136. The coils 122, 132, transistors 124, 134 and capacitors 126, 136 are selected so that the resonant frequency of the circuits 120, 130 is at about the frequency of the drive signals 152, 154 to maximize the efficiency of the power supply. In this embodiment, the drive signal frequency is about one megahertz, though other frequencies may be used. The drive signals 152 and 154 are supplied by a controller 150 such as a Unitrode UC3875QP or other similar product. The controller 150 receives the biasing power at pins 28 and 1 from the primary power supply circuit 160. Each of the coils 122 and 132 induce a varying magnetic field in the outer legs of the core 20. The secondary coil 212, which has a center tap 213, is coupled to a half wave rectifier bridge 214, which may comprise an MBRD66OCT, and then is coupled to a filtering circuit 216 comprised of a capacitor 218, an inductor 220, and capacitors 222 and 224 to provide a DC regulated output 226. The regulation is provided by feeding back to the controller 150 a signal modulated by a current sensing amplifier circuit 232 and a voltage sensing circuit 240 comprising the feedback circuit 230. To provide the carrier for modulation, a further secondary carrier coil 242 is coupled to one of the outer legs of the core 20. One of the legs of this transformer coil 242 is coupled to an isolation feedback transformer T2. The current sensing circuit takes the output of the center tap of the secondary coil 212 and provides a voltage drop across resistor R9 that is provided to current sensing amplifier circuit 232. The output of the current sensing amplifier circuit 232 is added to a voltage dropped across R13 and is provided to an amplifier 244 in the voltage sensing circuit 240. The other input in the voltage sensing circuit is a reference voltage developed by the zener reference diode 246 and also provided as a biasing level to the current sensing amplifier circuit 232. The output of the amplifier 244 is provided to the base of bipolar transistor Q3, which may be a MMBT2907T, configured in a common base configuration, to amplitude modulate the current through the secondary side coil 246. The primary side coil 156 of feedback transformer T2 is magnetically coupled to the secondary side coil of 246 and generates an amplitude modulated signal that is envelope detected and integrated to provide a feedback voltage at input 22 of the controller 150. As a result, as the amplitude of the envelope of the modulated signal increases, the voltage at input 22 of the controller 150 increases. When the controller 150 determines that the voltage has exceeded a predetermined limit, indicating that either the current or voltage at the output has increased beyond the predetermined maximum, the relative phase difference of driver signals 152 and 154 is increased. If the amplitude at input 22 decreases below a predetermined threshold indicating that the voltage or the current is below the desired levels, the relative phase of signals 152 and 154 is decreased towards zero to increase the voltage or current. Due to the summing effect of the magnetic flux at secondary coil 212, a highly efficient control or regulation of the power supply circuit is obtained. Because of the high efficiency that is attained with this circuit, heat dissipation is much less and it is possible to reduce the size of power supply to a much smaller form factor. In particular, each of the electrical components in Figure 2, other than the transformer, may be mounted using surface mount devices on a printed circuit board. Further, each of the inductors and transformer cores are low profile or planar cores mounted through cutouts formed in the printed circuit board. The coils of the inductors and transformers are provided by wiring traces on the circuit board that wrap around the portion of the appropriate core penetrating the circuit board. As a result, an extremely compact form factor may be obtained. Figure 4 shows a top planar view of such a printed circuit board with each inductor LI, L2 and transformer cores Tl and T2 identified. Notwithstanding the smaller size of the form factor, heat dissipation is not a serious problem due to the increased efficiency of the power supply according to the disclosed embodiments. Therefore, with all the components assembled on a printed circuit board as described above, the assembled printed circuit board may be housed within a housing formed from an injection molded plastic dimensioned 2.75 x 4.5 x 0.436 inches without undue heating of the housing, although other dimensions may be used with a key to maintaining a thin profile of the power supply being the ratio of the surface area of the top and bottom surfaces to the overall thickness of the housing. With proper heat sinks, for example, even smaller dimensions may be attained. For example, with such a housing, surface temperatures on the housing should not exceed one hundred twenty degrees Fahrenheit. A normal electrical plug such as a phased, three-prong plug, is coupled by an input cable (not shown) through a hole formed in the housing and an output cable (not shown) having a connector (not shown) coupled to the printed circuit board and to an output connector. Alternatively, the three-prong plug (not shown) may be formed within the housing with the prongs projecting from the housing to avoid the opening for a cable. Also, the plug may be of a pivotable type (not shown) mounted on the surface of the housing and rotate between a recessed position in a cutout formed within the housing and an in use position projecting at ninety degrees from the surface of the housing. Although the disclosed embodiment shows only one regulated DC voltage being supplied (for example +5 or + 16 volts DC), it would readily be understood by those of ordinary skill in the field that other regulated or unregulated voltages may also be supplied with minor modifications to the disclosed embodiment. For unregulated voltages, additional secondary coils (not shown) with the appropriate number of windings to provide the voltage may be magnetically coupled to any of the legs of the transformer core 120. The appropriate circuitry must then be provided for rectifying and filtering the output of this additional secondary coil. Similarly, an additional regulated voltage may be supplied by providing a feedback control circuit such as the type described above that provides the appropriate feedback. Figure 5 A shows a top planar view of a case 300 for an additional embodiment of the invention substantially having the shape of a right parallelepiped. The case may have dimensions of 5 inches long by 2.85 inches wide and the thickness (not shown) is 0.436 inches. Both the top portion of the case 300 and the bottom portion (not shown) define a number of louvers 304 defining multiple openings 302. The configuration of the openings 302 on both the top and bottom (not shown) portions of the cover are relatively unimportant. These openings must, however provide sufficient air circulation so that even when operating at maximum rated output power such as seventy-five watts DC, the surface temperature of the case 300 is less than one hundred and forty degrees Fahrenheit and preferably less than one hundred and twenty degrees Fahrenheit when the unit is operated at the maximum rated power of, for example seventy five watts DC. Having the openings defined on both the top and the bottom permits the user to operate the power supply in both the "right side up" and the "upside down" position with adequate air circulation. The case may be made of any high impact suitable plastics, such as Lexan or ABF, and when the top and bottom portions are assembled together such as by a snap lock or a force fit, they define a chamber in which all of the components are housed. Also, the exact dimensions are not critical, but preferably, the ratio of the top and bottom surface areas should be much greater than the thickness. Figure 5B shows a partial cross-section of top portion of the case 300. In preferred embodiments of the present invention, a thin layer 306 of material is connected to the bottom of the louvers 302 to cover the openings 304 that lead into the interior of the case 300. The thin layer 306 is thin enough to still allow heat to pass through the openings 304 using ordinary convection. However, the thin layer 306 is thick enough to prevent entry of liquids into the case 300, which could affect operation of the power supply. In preferred embodiments, the thin layer is 1 to 3 mils thick. However, in alternative embodiments, thinner or thicker layers may be used, so long as the layer is thick enough to resist penetration of liquids into the case 300 and as long as the layer is thin enough to permit normal heat dissipation by convection. In preferred embodiments, the thin layer 306 is formed from a plastic material, such as Lexan, ABF or the like from which the remainder of the case is also formed. However, in alternative embodiments, the thin film 306 may be formed from metals, composites, ceramics or other heat conductive and liquid resistant materials. In an assembled unit, immediately beneath the top (and above the bottom (not shown)) of the case 300 are heat sinks such as those shown in Figure 6. Each heat sink, which comprises a thin sheet of thermally conductive material such as aluminum (which may be anodized) is configured preferably to fit precisely within the top or bottom portions of the case and defines a number of cutouts. These cutouts may provide clearance for certain components to be directly cooled by air entering through the openings 304 defined between the louvers 302 or may be provided for clearance of the components mounted on the printed circuit board (not shown). Preferably, whatever pattern of cutouts are formed in the heat sink, the pattern should be positioned so that when the unit is assembled, the heat sink material should provide adequate coverage over the openings in the case 300 to resist penetration of spilled liquids into the assembled unit. This allows the unit to comply with Underwriters Laboratories and other safety standards. Alternatively, the top and bottom heat sinks may cover the entire power supply circuit board (not shown). Of course, other suitable materials besides aluminum may be used for the heat sinks. In preferred embodiments of the present invention, the undersides of the louvers are scalloped (either along the length of the louver 302 or from side to side of the louver 302) to provide an air gap between the louvers 302 and the heat sink to minimize conduction of the heat from the heat sink to the material of the case 300 and louvers 302. As shown in Figure 5B, the louvers 302 are spaced close together to form the openings 304 so that the openings 304 have a relatively narrow width. The width and depth of the openings 304 are chosen so that fingers cannot come into contact with either the thin layer 306 or the heat sinks under the thin layer 306. This minimizes the heat transfer to the user so that the touch temperature of the unit appears lower than the actual temperature. In preferred embodiments, the openings 304 are 3 to 5 mm, which is narrow enough to prevent the entry of fingers from small children. However, in alternative embodiments, narrower or wider openings 304 may be used, with the width being selected based upon the environment in which the power supply will be used. Fig. 5C illustrates a partial cross-section of another embodiment of the louvers in accordance with an embodiment of the present invention. In this embodiment, the louvers 310 are formed from a single piece of material with raised ridges 312 separated by depressions 314. The depressions are connected and secured to the heat sink 316 (such as those shown in Fig. 6) by adhesives, snap fit, simple contact or the like. The raised ridges 312 of the louvers 310 are spaced close together to form the depressions 314 so that the depressions 314 have a relatively narrow width. The width and depth of the depressions 314 are chosen so that fingers cannot come into contact with either the bottom of the depressions 314 or the heat sink 316. This minimizes the heat transfer to the user so that the touch temperature of the unit appears lower than the actual temperature. In preferred embodiments, the depressions 314 are 3 to 5 mm, which is narrow enough to prevent the entry of fingers from small children. However, in alternative embodiments, narrower or wider depressions 314 may be used, with the width being selected based upon the environment in which the power supply will be used. To minimize the transfer of heat from the raised ridges 312, an air gap 318 is formed beneath an undersurface 320 of the raised ridges 312 and the heat sink 316. The air gap 318 acts as an insulator so that the touch temperature of the case is lower than the actual temperature of the power supply heat sink 316. In preferred embodiments, the raised ridges 312 and the depressions 314 are formed from a plastic material, such as Lexan, ABF or the like from which the remainder of the case is also formed. However, in alternative embodiments, the raised ridges 312 and the depressions 314 may be formed from composites, ceramics or other heat conductive resistant and liquid resistant materials. Figures 7A and 7B show a schematic for the power supply circuit 800 with all resistance in ohms and all capacitance in microfarads unless otherwise labeled. The power supply is formed on a multilayer printed circuit board (not shown) having length and width dimensions that are only slightly smaller than the exterior of the case and fit as precisely as possible within the chamber of the case 300 sandwiched between the heat sinks to minimize movement after assembly. Further, as far as possible, surface mount devices are used to minimize the vertical dimension and all coil cores are preferably planar, low profile cores. Optimally, parts having the smallest possible thickness should be used. The power supply 800 includes an input circuit 810 that may be coupled to any AC power source preferably having a frequency of between about 50 to 90 hertz and preferably having a voltage of between about 90 to 240 Nolts AC. This input circuit 810 may include a full wave bridge rectifier 812, a filter circuit 814 and a regulation circuit 816 to provide an independent power supply for all integrated circuits used on the primary side 824 of the circuit. For filtering purposes, the input regulator circuit 816 may also include a center tapped coil 819 mounted on one of the exterior legs of the "E" planar core 822 of the transformer 820. (Preferably, the planar "E" core of the type shown in Figure 2 is used.) When the AC input voltage exceeds a predetermined range such as one hundred and forty volts RMS, transistor Q9 in cooperation with zener diode NR1 will cooperate so that the center tap of the coil 819 will be selected. This permits the output Nbias of the regulator to be in an acceptable range for higher input voltages such as may be common outside of the United States. The output Nbias is used for supplying power to all of the internal integrated circuits on the primary side 824 of the transformer 820, namely integrated circuits Ul and U2. This permits these integrated circuits Ul, U2 to continue functioning even if the DC output voltage from the power supply 800 drops below the range necessary for the integrated circuits Ul and U2 to continue operating. A controller integrated circuit Ul provides the four control signals for powering the MOSFETs coupled to the two primary coils 825 and 827 with their center taps coupled to Nbias. The outputs of integrated circuit Ul at pins 7 through 10 provide the control signals to a MOSFET driver circuit U2 such that MOSFETs Ql, Q2, Q4 and Q5 provide the appropriate phase control as is described in connection with Figure 8. Integrated circuit U2 may be for example a 4468 available from Micrel, Teledyne and Telcom. Each of power switching MOSFET transistor pairs Ql and Q2, and Q4 and Q5 are coupled to center tapped primary coils 825 and 827, respectively. These transistors preferably have heat sinks (not shown) coupled to their cases, and/or these heat sinks may also be thermally coupled to one of the heat sinks mounted immediately below and immediately above the top and bottom heat sinks for better thermal control. The capacitance of the MOSFETs Ql, Q2, Q4 and Q5 and the inductance of the coils 825 and 827 are selected to provide resonance at the frequency at which the drive signals are supplied, which may be about 1 MHz. Nonetheless, other frequencies may be used, for example, between a range of about 500 KHz to 2 MHz. Figure 8 shows a timing diagram of the signals at nodes L through Q shown on Figure 7 A and 7B. The integrated circuit Ul, as described in more detail below, through feedback, provides MOSFET driving signals L through O. The MOSFET driving signals provided to each primary winding, 825 and 827 (i.e., L and M for primary winding 825 and N and O for primary winding 827) are always one hundred eighty degrees out of phase as shown in Figure 8. However, the relative phase relationship of driving signal pair L and M for primary winding 825 with respect to driving signal N and O for primary winding 827 may be changed by the integrated circuit controller Ul in the manner described below to provided the regulated DC output voltage at connectors 846 and 848. Maximum power is provided when the pairs of driving signals are in phase with each other. It should be noted that while the control signal provided at pins 7 through 10 are preferably at substantially a fifty percent duty cycle, the resistors RIO through R13 and the capacitors CIO through C13 combine with the integrated circuit U2 to provide preferably driving pulses L through O with a duty cycle of less than 50 percent. This ensures that the FETS in a pair (i.e., Ql and Q2 for winding 825 and Q4 and Q5 for winding 827) are never both on at the same time to provide zero resonant switching and reduce power consumption. Due to the zero volt resonant switching design of the circuit, MOSFET pair Ql and Q2 are preferably never on the same time and MOSFET pair Q4 and Q5 are preferably never on at the same time. MOSFET Ql will turn on just about when the voltage at node P, which is at the drain of transistor Ql, reaches a minimum and will turn off immediately after the voltage at the drain of transistor Ql, goes above that minimum level. Similarly, due to the phase relationship of drive signal pair L and M at nodes L and M, transistor Q2 will only be on when the voltage at the drain is almost at the minimum. Transistor Q4 will also only be on when the voltage at node Q is virtually at its minimum and the transistor Q5 will only be on when the voltage at its drain is nearly at its minimum. It should be noted that the duty cycle of signals L through O is selected so that the waveforms P and Q are substantially trapezoidal with clipping occurring by transistors Ql, Q2, Q4 and Q5. This permits operation of the circuit over a wider range of input voltages. However, in alternative embodiments, transistors Ql, Q2, Q4 and Q5 need not clip so that the waveshapes at the drains of these transistors are substantially sinusoidal. Alternatively, using a low enough frequency for the drive signals, a square wave on the drains of the actual transistors could be used but would probably require larger cores. For the secondary side 826 of the power supply circuit 800, a single secondary winding 840 is located at the magnetic summing node of the core 822 (i.e., the center leg of the low profile "E" type core shown in Figure 2). That secondary winding 840 is coupled to a rectifier circuit 842 and then to an output filter 844 including a filter choke L2 to provide the regulated DC output at connectors 846, 848 in the manner described below. The center tap of the secondary winding 842 is coupled through a coil in the filter coil L2 sharing a common core with the coil in the output filter 844. Through resistor R23, this center tap of winding 842 provides a current sense input to a summing amplifier U3A. A voltage sense of the output DC regulated voltage Nout is provided to an amplifier including amplifier U3C. The sensed voltage signal at the output of amplifier U3C is provided to the summing amplifier U3 A through amplifier circuit U3B to provide the feedback necessary for the desired regulation of the DC output. The output of the summing amplifier U3A is provided through an emitter follower transistor Q7 to the center tap of the secondary side 826 of the feedback transformer 850. This transformer is magnetically isolated from the transformer 820. The signal at the center tap of transformer 850 amplitude modulates a carrier signal provided by winding 852 provided on the same exterior leg of the core 822 as primary winding 827. Preferably also, this should be the opposite exterior leg of the core 822 on which coil 819 and winding 825 are mounted. The primary side 824 coil of transformer 850 provides an amplitude modulated feedback signal that has an amplitude envelope. A diode detector comprised of diode CR5 and resistor RI 7 strip the carrier away, leaving the amplitude envelope as a feedback control signal to the NMOD input (pin 1 of Ul) to provide the feedback useful for altering of the phase relationship between the drive signal pairs of signals L and M on the one hand, and signals Ν and O, on the other hand to regulate the DC power supply output at connectors 846, 848. With the current control connector 860 and the voltage control connector 862 left unconnected (as shown), amplifiers comprising U3B and U3D along with the current and voltage sense signals cause the integrated circuit Ul to control the phase relationship between the drive signal pairs L and M, on the one hand, and Ν and O, on the other hand, to provide a constant power supply until the output voltage drops below about ten volts. Then, due to the feedback signal at pin 1 of the controller Ul, the integrated circuit controller Ul controls the relative phase relationship between the pair of drive signals L and M, on the one hand, and Ν and O, on the other hand, to provide a constant current source down to a minimal voltage, which is preferably less than about one volt. It should also be noted that the Ncc used by the amplifiers U3A through U3D in the integrated circuit U3 and the voltage regulator U4 to generate the +5 volts used in the control circuit (e.g. comprising amplifiers U3B, U3C and U3D) is supplied by a rectifier circuit 854. The rectifier circuit 854 is also coupled to secondary coil 852. Figure 9 shows a block diagram 900 of the controller integrated circuit Ul . Pins 13, 14, and 15 cooperate together along with external components R3, R4, R5 and R6 to set the operational frequency of the oscillator 902 to be preferably at 2 MHz, although other frequencies may be selected. An output of the oscillator 902 is coupled to an internal capacitor 901 to provide a triangle signal labeled Ramp on Figures 10A and 10B while another output of the oscillator 902 is a 2 MHz square wave coupled to exclusive OR gate 904 and the clock input of a D flip flop 907. A Schmitt trigger comparator 906 compares the feedback signal NMOD at pin 1 with the ramp signal as is shown in Figures 10A and 10B. In Figure 10 A, the NMOD signal, which is the envelope of the feedback signal from the feedback transformer 850 is at the maximum level, while in Figure 10B, the NMOD signal is somewhat less than the maximum. As can be seen in Figures 10A and 10B, the comparator 906 cooperates with the D flip flop 907, the exclusive OR gate 904, and the associated logic gates 908 to generate one shot control signals J and K. As can be seen by comparing Figures 10 A, when NMOD is at a maximum, the one shot drive signals J and K are controlled so that both one shot control signals go high at the same time. When the amplitude of NMOD drops below the maximum, the timing of the one shot control signal J is retarded and the timing of the one shot control signal K is advanced. These one shot control signals J and K are provided to one shot circuits 920 and 930 within the controller circuit Ul, which have dual outputs NA and NC and NB and ND respectively. The one shots 920 and 930 trigger on the rising edge of signals J and K respectively, and the durations to the falling edge of the control signals J and K are irrelevant provided that they fall before the one shots need to be retriggered. Due to the inclusion of inverters 922 and 932, the output pair of signals NA and NC and NB and ND are approximately one hundred and eighty degrees out of phase. It should also be noted that the external capacitor C7 and resistor R7 are coupled to pins 5 and 4 of the controller Ul to control the duration of the output pulses at the one shot 920 and the one shot 930 to trigger them for the same duration. Further, these component values are selected to be as near as possible to provide a fifty percent duty cycle on the outputs L through O of the MOSFET driver circuit U2 at the frequency of operation. The controller circuit Ul also includes a reference voltage generator 940 that provides the reference voltage for the over voltage protection circuit 942 and the comparator 944. As shown in Figure 7, an over voltage protection circuit 830 having a coil 832 is located at or near the summing node of the E block core 822. The value of the components within over voltage protection circuit 830 are selected such that if the output voltage DC Output goes above a predetermined threshold, silicon controlled rectifier (SCR) Q3 will fire, shunting the Nbias to ground. This will cause the integrated circuits Ul and U2 to cease operating, thereby shutting down the output until the unit is recycled by temporarily removing the AC input voltage. Thus, a small, highly efficient form factor power supply has been disclosed that may be readily mounted within a small container having a thickness of 0.436 inches or less and having dimensions suitable for holding in a typical shirt pocket or calculator pocket in a briefcase at high power levels of up to about 75 watts DC output with a surface temperature of about 140 degrees Fahrenheit at the surface. Thicknesses of less than 0.436 inches may be attainable if thinner electrolytic or other types of filtering capacitors can be obtained using standard production techniques. Alternatively, a thinner case may be obtained by maximizing coupling of heat generating components to the heat sinks with maximum air flow through the openings defined by the louvers 302 and by making the top and bottom surface areas of the case larger. Regulation of the output voltage may be readily attained. Still further, the secondary coil can be positioned where the magnetic flux induced in the core from the two primary coils destructively interfere with each other and where the phase of the two driving signals is approximately one hundred eighty degrees out of phase at maximum output. In further alternatives, cooling methods other may be used, such as small electric fans, thermal-electric coolers or the like, to permit smaller form factor power supply configurations. Other alternatives will be readily apparent to those of skill in the art. It should be noted that in alternative embodiments, the various resistors, capacitors, frequencies and inductors may be different and other types of integrated circuits may also be used. Figures 12-16 illustrate an improved transformer core 1010 in accordance with an embodiment of the present invention. Figure 12A shows a top plan view of the transformer core 1010, which is formed by a base plate 1012, a secondary leg 1014 and a pair of primary legs 1016 and 1018. The secondary leg 1014 and the primary legs of the transformer 1010 may be bosses attached to the base plate 1012 by welds, magnetically permeable adhesives, or the like, or the entire assembly may be molded using magnetically permeable powder. Figure 12B and 12C show two side plan views of how the transformer legs 1014, 1016, and 1018 are positioned on the base plate. Figure 13A shows a top plan view of a transformer cap 1020, which is secured to the legs 1014, 1016, and 1018 of the transformer core 1010 to complete the transformer core once the bosses have been inserted through cutouts. The transformer legs 1014, 1016, and 1018 are secured to the transformer cap 1020 by magnetically permeable adhesives, welding or the like. Figures 13B and 13C show side plan views of the transformer cap 1020. In preferred embodiments, the transformer core 1010 and transformer cap 1020 are formed from a ferrite material. The operational frequency range of the core is from about 0.5 to 1.0 MHZ. Also, the initial magnetic permeability is preferably 1400 ± 20%. In addition, the saturation flux density may be 5300 gauss, and the Curie temperature may be 250 degrees Centigrade. The core loss while operating at a frequency of 1 MHZ should preferably be approximately 500 KW/m at 500 gauss. In other embodiments, different core parameters may be used. In the disclosed embodiments, the base plate 1012 and the transformer cap are dimensioned to be 1.260 x 1.260 x .075 inches. The secondary transformer leg 1014 is dimensioned to be 0.800 x 0.200 by 0.060 inches, and each primary transformer leg is 0.133 x 0.700 x 0.060 inches. The secondary transformer leg 1014 is positioned away from the primary transformer legs 1016 and 1018, as shown in Figures 12A-12C, to maximize the cross- sectional area of each of the transformer legs (i.e., the length and width of the transformer legs). This maximizes a ratio of the cross-sectional area of the transformer legs to the windings, thereby requiring less windings for the same magnetic coupling. Fewer windings means less area of a layer of a circuit board may be used so that the number of layers on the circuit board may be minimized. The improved transformer core also provides this maximized ratio while maintaining the ratio of the secondary to the primary windings at a constant value. However, in alternative embodiments, slightly different dimensions for the core parts may be used. Also, as described in the previous embodiments, the secondary coil is still positioned at a summing point of the primary coils. Figure 14 shows a printed circuit card layer 1030 without secondary or primary cores attached and having cutouts 1014', 1016' and 1018' to allow the corresponding transformer legs 1014, 1016 and 1018 to pass through the printed circuit board. Figure 15 shows another printed circuit card layer 1030" in which a secondary coil pattern 1040 surrounding the cut-out 1014' for the secondary transformer leg 1014. Figure 16 shows still another printed circuit card layer 1030' in which primary coil patterns 1042 and 1044 surround the cut-outs 1016' and 1018' for the to primary transformer legs 1016 and 1018, respectively. Figures 17-22 illustrate an alternative embodiment using two transformer cores 1110 in accordance with the present invention. Figure 17A shows a top plan view of bottom portion of the transformer core 1110, which is formed by a base plate 1112, a central leg 1114 and a pair of peripheral legs 1116 and 1118. The central leg 1114 and the peripheral legs of the transformer 1110 may be bosses attached to the base plate 1112 by welds, magnetically permeable adhesives, or the like, or the entire assembly may be molded using magnetically permeable powder. Figure 17B and 17C show two side plan views of how the transformer legs 1114, 1116, and 1118 are positioned on the base plate 1112. Figure 18 A shows a top plan view of a transformer cap 1120, which is secured to the legs 1114, 1116, and 1118 of the transformer core 1110 to complete the transformer core once the bosses have been inserted through cutouts. The transformer legs 1114, 1116, and 1118 are secured to the transformer cap 1120 by magnetically permeable adhesives, welds or the like. Figures 18B and 18C show side plan views of the transformer cap 1120. In preferred embodiments, the transformer core 1110 and transformer cap 1120 are formed from a ferrite material that has properties and characteristics that are similar to those of the embodiment with the transformer core 1010, discussed-above. In the disclosed embodiments, the base plate 1112 and the transformer cap 1120 are dimensioned to be l.113 x l.113 x .075 inches. The central transformer leg 1114 is dimensioned to be 0.300 x 0.300 by 0.060 inches, and each peripheral transformer leg is 0.075 x 0.630 x 0.060 inches. The central transformer leg 1114 is positioned away from the peripheral transformer legs 1116 and 1118, as shown in Figures 17A- 17C, to maximize the cross-sectional area of the central transformer leg 1114 (i.e., the length and width of the central transformer leg). This maximizes a ratio of the cross-sectional area of the central transformer leg 1114 to the windings, thereby requiring less windings for the same magnetic coupling. Fewer windings means less area of a layer of a circuit board may be used so that the number of layers on the circuit board may be minimized. The improved transformer core also provides this maximized ratio while maintaining the ratio of the secondary to the primary windings at a constant value. Also, as described in the previous transformer core 1010 embodiment, the secondary coil is still positioned at a summing point of the primary coils. Figure 19 shows a printed circuit card layer 1130A defining a secondary coil 1040' and having cutouts 1114', 1116' and 1118' and cutouts 1114", 1116" and 1118" to allow the corresponding transformer legs 1114, 1116 and 1118 of two transformer cores 1110 to pass through the printed circuit board. The secondary coil pattern 1140' passes around both central leg cutouts 1114' and 1114" to magnetically couple the secondary coil pattern 1040' with the summing point of two primary coils (see Figures 20 and 21). Figure 20 shows another layer 1130B of the printed circuit card in which two primary coil patterns 1142' and 1142" surround the corresponding central cutout 1114' and 1114", respectively. Figure 21 shows another printed circuit card layer 1130C in which two additional primary coil patterns 1144' and 1144" surround the corresponding central cutout 1114' and 1114", respectively. It should be noted that primary coil patterns 1144' and 1144" are coupled to corresponding primary coil patterns 1142' and 1142" to form the two primary coils that drive the secondary coil. Figure 22 shows still another printed circuit card layer 1130D in which a secondary coil pattern 1140" surrounds the corresponding central cut-out 1114' and 1114", respectively. It should be noted that secondary coil pattern 1140' is coupled to the corresponding secondary coil pattern 1140" to form the secondary coil that is coupled to the primary coils. Finally, it should be pointed out that the ancillary coil patterns 1146 surrounding the peripheral legs 1116' and 1116" are provided to produce a signal useful for protecting the circuit from over voltage. The applicant has found that this characteristic power and current curve provides good charging of lithium ion, nickel metal hydride, nickel cadmium and other rechargeable batteries. Thus, the small form factor power supply is capable of supplying sufficient power to a personal computer or the like, even when the batteries are thoroughly discharged. The constant current at the output connectors 846, 848 can provide minimal voltages down to about less than one volt because the controller Ul can attain relative phase shifts between the drive signal pairs to between about one degree to one hundred eighty degrees (i.e., signal N lags signal L between about one degree to one hundred eighty degrees and signal O and lags signal M between about one degree and one hundred eighty degrees). Thus, as shown in Figure 11, if one were to draw a power versus output current curve and an output voltage versus output current curve of such a power supply, the slope of the output voltage curve is relatively constant until the output current reaches approximately 2.0 amperes, then slopes down to 10 volts at which time the output current is essentially constant at approximately 3.6 amperes for voltages under 10 volts. The output power curve increases relatively linearly until the current level reaches approximately 2.2 amperes, at which time the output power curve tends to level off until the current reaches it maximum value of approximately 3.6 amperes. Therefore, the power supply is capable of providing constant current to the personal computer or the like, even if the battery is only capable of producing a fraction of a volt. This power curve is determined as a result of the selected amplifier configuration associated with integrated circuit U3, which may be an LM 324 on the secondary side 826. The predetermined limit may be as high as 75 watts DC for a power supply having an upper and lower surface area within the case 300 of about 14 square inches and a thickness of about 0.436 inches or less so that the ratio of the top or bottom surface areas to the thickness is about 30:1. However, the circuit can readily be programmed to provide other power/current characteristics, such as the power characteristics for lap top computers, appliances, cellular or portable telephones, notebook computers, game systems or the like. This may be accomplished by coupling additional resistors to ground and/or +5 volts (generated by a voltage regulator U4) to the current control and voltage control inputs. Alternatively, as shown in Fig. 23, the current control input 860 and voltage control input 862 (see Fig. 7) can be coupled through a cable 882 to control circuits 884 commonly contained within the rechargeable batteries 886 coupled to the DC output connectors 846 and 848. These control circuits 884 may contain amplifiers 888, resistors 890, digital to analog converters or any other analog signal generator that may be coupled to the current and voltage control inputs 860, 862 through the cable 882 coupled to the battery terminals for charging. This would permit the controller in the battery programmatically to regulate the voltage and the current provided at the DC output to minimize recharging time based upon the known characteristics of the battery. Preferably, the programing of the small form factor power supply is carried out using either resistive programing or analog programing. However, in alternative embodiments, other programing methods may be employed, such as digital or microprocessor controlled programing (with or without resistance ladder networks), with the type of programing technique being dependent on the power requirements of the device. Figure 24 is a schematic of a programing circuit in accordance with an embodiment of the present invention that is used to resistively program the power supply to produce between 0 and 16 volts, and Figure 25 is a schematic of another programing circuit in accordance with an embodiment of the present invention that is used to resistively program the power supply to produce between 16 and 18 volts. Figure 26 is an end view of a connector that mates with the small form factor power supply (shown in Figures 3 and 7) and is useable to program the small form factor power supply, as shown in Figures 24 and 25. As shown in Figures 24 and 25, the power supply may be programmed remotely to provide the required power at voltages between 0 to 18 volts using various external cables having built in resistances that program the power supply to output the required power level (i.e., voltage and current). This method allows the small form factor power supply to be programmed for any value of voltage and/or current by connecting a resistor from the voltage and/or current programming pins (e.g., pins 1 and 4) to ground (e.g., pin 3) as shown in Figure 24, or from the voltage programming pin (e.g., pin 1) to Nouτ (e.g., pin 4) for voltages above 16 volts as shown in Figure 25. To program the voltage between zero and 16 volts, as shown in Figure 24, the following formula is used: where R = the programming resistance between pins 3 and 4 (in Kohms); and where voltage. To program the output voltage between 16 and 18 volts, as shown in Figure 25, the following formula is used: where R= the programming resistance between pin 2 and 4 (in Kohms); and where voltage. To program the output current between 0 and 3.6 amps, as shown in Figures 24 and 25, the following formula is used: 10 where R=programming resistance between 1 and 3 (in Kohms); and where Iouτ-ouput current In another method, analog programming of the small form factor power supply is used. This method allows the small form factor power supply to be programmed for any value of voltage and/or current by providing an analog voltage signal from the respective programming pins and ground. To program the output voltage between 0 and 18 volts, the following formula is used: where N P =programming voltage applied to pin 4 with respect to pin 3; and where Nouτ ~ output voltage. To program the output current between 0 and 3.6 amps, the following formula is used: where Ip=programming voltage applied to pin 1 with respect to pin 3 ; and where Iouτ = output current. In addition, the power supply may interface with a programmable current generator interface, such as an MC33340 fast charge battery controller manufactured by Motorola, Inc. of Schaumberg, IL or a BQ2002C manufacture by Benchmarq, Dallas, TX. This allows the cable to directly interface with the power supply, while performing the functions of charge termination or trickle charging. In preferred embodiments, there is a V2 power factor available. The cable includes a chip that is adapted to work with a specific device, such as a cellular telephone, laptop computer or the like, so that the charging characteristics of the power supply are altered as needed by simply changing cables. Alternatively, a generic cable can be used and an adapter may be connected to the power supply between the cable and the power supply that contains different resistors that program the power supply to provide a desired power supply. Typically, precise charge termination is difficult to detect when the battery reaches saturation. Thus, preferred embodiments of the present invention detect the knee of the power curve shown in Figure 11 and reduce the current to deliver at a more steady rate. Figures 27(a) - 34® show various cables with connectors in accordance with embodiments of the present invention that program the small form factor power supply for supplying power to different devices. These cables have a connector 1500 for connecting with the small form factor power supply and use various configurations of resistances and wire connections to program the small form factor power supply to work with various devices. In these figures, NC=no connection, +DC=Nouτ (e.g., from pin 2 of Figure 26), CC=I P rogram (e.g., from pin 1 of Figure 26), (e.g., from pin 4 of Figure 26), and GΝD=ground (e.g., from pin 3 of Figure 26). Figures 27(a) - 27® show views of a cable 1502 having a connector 1504 for use with IBM computers, such as the "ThinkPad" or the like. No resistances are provided in the connectors 1500 and 1504, since the IBM computers provide their own power regulation, and the pins from the small form power supply (e.g., Figure 27(c)) are converted to a compatible connector and pin out, as shown in Figure 27(b). Figures 28(a) - 28 ® show views of a cable 1506 having a connector 1508 for use with IBM computers, such as the "ThinkPad" or the like, and for Compaq computers, such as the Armada or the like. No resistances are provided in the connectors 1500 and 1508, since the IBM and Compaq computers provide their own power regulation, and the pins from the small form power supply (e.g., Figure 28(c)) are converted to a compatible connector and pin out, as shown in Figure 27(b). Figures 29(a) - 29 ® show views of a cable 1510 having a connector 1512 for use with for Compaq computers, such as the Contura, LTE or the like, Toshiba computers, such as the Satellite and the Portege, Gateway computers, such as the Solo, and Hitachi computers, such as the C120T and the like. Either the connector 1500 or the connector 1512 use resistances between pins 2 and 4 of the small form factor power supply to program the small form factor power supply. Figures 30(a) - 30(b) show views of a cable 1514 that does not have a connector. The end 1516 of the cable 1514 is left with bear wires to be configured to work with various computers that don't use the resistances or connectors shown in the other cables. Since the cable 1514 has no end connector, it can be wired to match various computer configurations. Figures 31(a) -31 ® show views of a cable 1518 having a connector 1520 for use with another configuration of a computer. Either the connector 1500 or the connector 1520 use resistances between pins 1, 3 and 4 of the small form factor power supply to program the small form factor power supply. Figures 32(a) - 32® show views of a cable 1522 having a connector 1524 for use with Hewlett Packard computers, such as the Ominibook or the like. Either the connector 1500 or the connector 1524 use resistances between pins 3 and 4 of the small form factor power supply to program the small form factor power supply. Figures 33(a) - 33® show views of a cable 1526 having a connector 1528 for use with Toshiba computers, such as the Tecra or the like. Either the connector 1500 or the connector 1528 use resistances (having a different value than those for cable 1522) between pins 3 and 4 of the small form factor power supply to program the small form factor power supply. Figures 34(a) - 34® show views of a cable 1530 having a connector 1532 that is designed to be a universal cable that accepts various connector ends that can mate with different device. No resistances are provided in the connectors 1500 and 1532, since the cable 1530 is converted to be compatible with various devices based on the connector adapters connected to the connector 1532. Figures 35(a)-40® show various connector adapters for use with the female connector 1532 of the cable 1530 shown above in Figures 34(a)-34(c). Figures 35(a) - 35© show a connector adapter 1534 having a male connector 1536 for connecting with the connector 1532 and has an end connector 1538 that converts the generic cable 1530 of Figures 34(a) - 34® to correspond to the cable 1502 shown in Figures 27(a) -27(c). Figures 36(a) - 36® show a connector adapter 1540 having connectors 1536 and 1542 that convert the generic cable 1530 of Figures 34(a) - 34© to correspond to the cable 1506 shown in Figures 28(a) - 28(c). Figures 37(a) - 37© show a connector 1544 having connectors 1536 and 1546 that convert the generic cable 1530 of Figures 34(a) - 34 © to correspond to the cable 1510 shown in Figures 29(a) - 29(c). Figures 38(a) - 38® show a connector adapter 1548 having connectors 1536 and 15505 that convert the generic cable 1530 of Figures 34(a) - 34© to correspond to the cable 1518 shown in Figures 31(a) - 31(c). Figures 39(a) - 39 © show a connector adapter 1552 having connectors 1536 and 1554 that convert the generic cable 1530 of Figures 34(a) - 34© to correspond to the cable 1522 shown in Figures 32(a) - 32(c). Figures 40(a) - 40 © show a connector adapter 1556 having connectors 1536 and 1558 that convert the generic cable 1530 of Figures 34(a) - 34© to correspond to the cable 1526 shown in Figures 33(a) - 33(c). Figures 41 (a) and 41 (b) illustrate a block diagram and a schematic of an interface for providing power to more than one device at a time. As shown in Figure 41 (a), a small form factor power supply 2000 is connected through a cable 2002 to an interface 2004 that supports more than one device at a time by the power supply. The interface 2004 can support two or more devices, with the number of devices being dependent on the number of power output ports. The power to each device is controlled by cable connections to each device, such as the cables and connectors described above in Figures 27(a) - 40(c). As shown in Figure 41(b), the interface 2004 receives the cable 2002, which has a first voltage wire 2006 providing a first voltage NI and a second voltage wire 2008 providing ground G. This is generally connected to the primary device. Additional devices are connected to wires 2006 and 2008 through taps 2010 and 2012. Tap 2012, if necessary, feeds into a voltage regulator to change the voltage to that desired by the device and outputs a second voltage on wire 2014 and ground on wire 2016. In alternative embodiments, the additional regulator may be provided in the cable used for each device. Figures 42-44 show various perspective views of a small form factor power supply 3000 that has been configured for use with portable telephone equipment in accordance with an embodiment of the present invention (note: these drawings are from 3 -Dimensional CAD drawings and the many lines in the drawings indicate curves on the small form factor power supply and do not represent surface features). Figures 45 and 46 show perspective views of the small form factor power supply 3000 connected to a cellular telephone battery and telephone. The small form factor power supply 3000 is directed to charging portable telephone batteries. It has a housing 3002 similar to that described above and uses the charging circuitry described above. However, in alternative embodiments, different charging topologies may be used, depending on the charging environment, the battery type and the weight requirements of the small form factor power supply. Embodiments of the small form factor power supply can be adapted to work with telephones manufactured by Audiovox, Ericsson/GE, Fujitsu, JRC, Mitsubishi/Daimondtel, Motorola, Murata, NEC, Nokia, Novatel, Oki, Panasonic, Sony, Uniden, AT&T, Tandy, Pioneer, JVC or the like. Also, the small form factor power supply can be used with a wide variety of portable telephone equipment, such as cordless telephones, cellular telephones, radio telephones, PCS telephones and the like. The housing 3002 of the small form factor power supply 3000 includes a foldable AC plug 3004 that is adapted to plug into a standard electrical socket (not shown) to receive power, from standard lines, that is to be transformed and supplied to an attached device. Alternative embodiments may use different plugs to handle different voltages and/or different country's electrical socket and power configurations. As shown in Figure 42, the AC plug 3004 folds into a recess 3006 when not being used. The AC plug 3004 is unfolded by engaging and rotating a tab 3008 to rotate the AC plug 3004 out of the recess 3006. In alternative embodiments, the AC plug may be spring loaded and utilize a catch to lock the AC plug in the folded down position and once the catch is released the spring rotates the AC plug into the unfolded position. The AC plug 3004 may include detentes or use other methods to maintain the AC plug 3004 in the folded or unfolded position. Once unfolded, the AC plug 3004 can be inserted into the socket, and the housing 3002 generally hangs down against a wall for stability and support. In alternative embodiments, the AC electric plug may be recessed and fixed in the housing of the small form factor power supply 3000 to receive an electrical cord that is attached between the AC plug and an electric socket. As shown in Figures 42 and 43, a power output 3010 is adapted to fold out and includes a plurality of contacts 3012 that mate with the corresponding contacts (not shown) on a portable telephone equipment battery 3011. In preferred embodiments, the contacts 3012 of the small form factor power supply 3000 are placed in electrical contact with the contacts on the back of the battery 3011. Alternatively, when the battery 3011 is not coupled to portable telephone equipment, the contacts 3012 of the small form factor power supply may be placed in electrical contact with the contacts of the battery 3011 that provide power to the portable telephone equipment. To unfold the power output 3010, the user pushes the power output 3010 through a port 3014 to force the power output 3010 to rotate down about a hinge 3016. The power output 3010 may be spring loaded with a catch, detentes or other methods to lock the power output 3010 in the folded or unfolded position. In alternative embodiments, the small form factor power supply 3000 may use a recessed connector that connects to either the portable telephone equipment or battery using a cable such as described above and below. The small form factor power supply 3000 also has support legs 3018 that include ends with guide tabs 3020. The guide tabs 3020 are shaped to engage with channels 3021 on the portable telephone equipment battery 3011 to hold the battery 3011 in electrical contact with the small form factor power supply 3000 during charging. The support legs 3018 are also capable of holding a portable telephone connected to the battery 3011, as shown in Figures 45 and 46. The support legs 3018 are rotated out when the small form factor power supply 3000 is to be connected to a battery 3011. To attach the small form factor power supply 3000, as shown in Figure 45 and 46, the user slides the battery 3011 to engage the channels 3021 of the battery 3011 with the guide tabs 3020 of the support legs 3018. The user then slides the battery 3011 back, until it is stopped and contacts the power output 3010. In preferred embodiments, each of the support legs 3018 rotates independently of the other to simplify manufacturing and reduce complexity of the small form factor power supply 300. However, in alternative embodiments, the support legs 3018 may rotate out together as a unit and/or rotate out when the power output 3010 is rotated. In preferred embodiments, the small form factor power supply 3000 is capable of charging most telephone equipment batteries in less than 15 minutes. However, the actual charging time will vary based on the size of the battery and the battery chemistry. Most batteries (providing between 1 to 15 hours of high power operation) charge in 5-30 minutes. The small form factor power supply 3000 includes a temperature sensor that is included in the small form factor power supply control chip to charge the battery as described above. This temperature sensor allows the small form factor power supply to determine the proper charging rate for a battery and avoid generating undue heat by overcharging or charging at too high a rate. In further embodiments, the small form factor power supply can be used to power the portable telephone equipment simultaneously with charging of an attached battery. Alternatively, the small form factor power supply may be able to power the portable telephone. In the embodiment of Figures 42-46, the AC plug 3004, the power output 3010, and the support legs 3018 are all designed to be folded in when the small form factor power supply 3000 is not in use. This minimizes the profile of the small form factor power supply when it is not in use and makes it easier to transport. In alternative embodiments, the AC plug, the power output and the support legs may be formed or maintained in the unfolded position, where the smaller profile is not needed or an advantage. Figure 47-50 show a perspective and plan views of a small form factor power supply adapter connector 4000 for use with portable telephone equipment in accordance with embodiments of the present invention (note: these drawings are from 3 -Dimensional CAD drawings and the many lines in the drawings indicate curves on the small form factor power supply and do not represent surface features). The adapter connector 4000 has a housing 4001 that includes a connector 4002 configured to mate with the connector 1532 of cable 1530 shown in figures 34(a) - 34(c). This adapter connector provides an upgrade path for users that already posses a small form factor power supply, as described above. As shown in Figures 47-50, the adapter connector 4000 includes a plurality of contacts 4006 for connecting with corresponding contacts (not shown) on a portable telephone equipment battery. The housing 4001 may also contain additional circuitry or electronics needed to properly program a small form factor power supply to charge a portable telephone equipment battery. The adapter connector 4000 includes leg supports 4008 with guide tabs 4010 that engage with channels on a battery (similar to those shown in Figures 45 and 46 above). To secure the adapter connector 4000 to a battery, an end clip (not shown) attached to the adapter connector 4000 by elastic straps (not shown), or the like. The elastic straps are threaded through eyelets 4011 so that the adapter connector 4000 can not slip off the battery. In the illustrated embodiment, the leg supports 4008 are foldable about a hinge 4012 to reduce the profile of the adapter connector 4000 when not in use and/or when being transported. In alternative embodiments, the support legs 4008 may be formed in a fixed open position. The small form factor power supplies described above are capable of charging various different types of batteries, such as NiCad and NiH. However, in alternative embodiments, the small form factor power supplies may charge batteries using Zinc air, Lead acid, alkaline or the like. The power supply may also be used to charge Lithium ion batteries, although a different control chip or circuitry may be required to handle the unique charging requirements of these batteries. While embodiments of the present invention are directed to a form factor power supply in particular, other embodiments of the present invention are directed more generally to power supplies which are programmable to provide power to any one of a number of electronic devices having differing input power requirements. The embodiment discussed above with reference to Figures 7A and 7B includes a power supply which is programmable to provide a power output at a terminal 846 at a suitable operational current or operational voltage associated with the particular electronic device which is to be powered. The appropriate programming signal can then be applied to either terminal 860 or 862 using, for example, an appropriate connector associated with the device to receive power as discussed above with reference to Figures 23 through 41. Figure 51 illustrates a schematic of an alternative embodiment of a programmable power supply 5000 which receives input power from a DC power source and controls the output power using a pulse width modulation technique. Resistances are expressed in ohms and capacitances are expressed in micro farads unless noted otherwise. A DC input source such as a 12 volt automobile cigarette lighter is provided across terminals 5011 and 5012. Other embodiments may be adapted to receive power from other DC sources such as, for example, a DC power source in the passenger compartment of an airplane at different voltages such as 15 volts. The input circuitry of the embodiment shown in Figure 51 differs from the embodiment shown in Figures 7A and 7B by, among other things, replacing the input transformer and full bridge rectifier circuit with a single inductor L21 in a Buck regulator topology. A transformer T21 includes a primary coil 5002 and a secondary coil 5004. The primary coil 5002 receives current from the inductor L21. This current through the primary coil 5002 induces an output current through the secondary coil 5004 to an output terminal 5864. A switch transistor Q61 controls the current through the primary coil 5002 to affect the output current induced in the secondary coil 5004. An integrated circuit U21 opens and closes the switch transistor Q61 to pulse width modulate the current through the primary coil 5002. The integrated circuit U21 may be an integrated circuit number UC3845 sold by Unitrode. The integrated circuit U21 is preferably configured to provide fixed width pulses at an output pin 6 during which the switch transistor Q61 is closed to provide a pulse of current through the primary coil 5002. The integrated circuit U21 then receives an input signal at a terminal 2 to control the duty cycle of the pulse signal provided at the output pin 6. Accordingly, by increasing or decreasing the duty cycle of the pulse signal provided at the output pin 6, the output current induced in the secondary winding 5004 may be increased or decreased to maintain the output power at terminal 5864 at an appropriate operational voltage or current level. The output current of the secondary coil 5004 is then smoothed by capacitors C161 and C201 to provide a DC power output to the output terminal 5864. Terminals 5848, 5860, 5862 and 5864 are preferably provided to a connector coupling the power supply 5000 to the electronic device to be powered. In a manner similar to the embodiment discussed above with reference to Figure 7 A and 7B, the terminal 5860 provides a current control input and the terminal 5862 provides a voltage control input. Connectors, such as those discussed above with reference to Figures 23 through 41, may then provide a programming signal to the current control input 5860 or the voltage control input 5862. In response to these inputs, a voltage is applied to a terminal 2 of the integrated circuit U21 to control the duty cycle of the pulse signal output transmitted at output pin 6. The current through the secondary coil 5004 is therefore controlled to provide an operational voltage or operational current at the power output pin 5864. While the embodiment shown at Figure 1 is configured to receive a DC power input, this embodiment could be modified to accept an AC power input by, for example, replacing the input circuit having the inductor L21 with an input transformer followed by a full bridge rectifier as illustrated in Figures 7A and 7B. Also, the aforementioned small form factor design illustrated with reference to Figures 7A through 41 may be modified to accept a DC input by, for example, replacing the input transformer and full bridge rectifier circuit with a single inductor as shown in the embodiment of Figure 51. Figure 52 shows an embodiment of a form factor power supply 6000 in which a detachable two prong plug 6002 may be inserted into the form factor power supply 6000 at connection terminal 6008. The plug 6002 may then be inserted into a wall socket 6004 to enable the form factor power supply 6000 to deliver power to a portable electronic appliance through a connector 6006. Figure 53 shows an embodiment which a secondary adapter 6100 may be inserted into the form factor power supply 6000 in lieu of the plug 6002. The secondary adapter 6100 is adapted to receive a low voltage DC input (e.g., between about 12 and 15 volts) which is converted to an intermediate power signal at a higher voltage at a terminal 6104. This intermediate power signal may then be applied in lieu of the AC power source provided by the wall socket 6004. The secondary adapter 6100 may be of a similar thickness and width as that of the form factor power supply 6000 so that when the secondary adapter 6100 and the primary adapter 6000 are coupled together, they form a continuous unit. The secondary adapter includes a power terminal 6102 for receiving a connector to a DC power source. Figure 54A-C illustrate three views of the secondary adapter 6100 shown in Figure 53. A connector 6106 may be coupled to the input terminal 6102 to provide a DC power source such as a cigarette lighter of an automobile or a 15 volt DC power source from a passenger compartment of an aircraft such as a 15 volt DC power source manufactured by Empower. The circuitry in the form factor power supply 6000 for converting a high voltage power signal to a low voltage power signal may have a topology such as that shown in Figures 3 A and 3B, or Figures 7A and 7B. However, the application of a secondary power adapter such as the secondary power adapter 6100 may be applicable to many different circuit topologies which are adapted for converting a high voltage AC power signal (e.g., between about 100 volts and 300 volts) to a low voltage power signal for powering an electronic appliance. Figures 55 and 56 illustrate exemplary embodiments for the circuitry in the secondary adapter 6100 for converting a low voltage DC signal to a high voltage power signal provided to a power adapter designed to receive a high voltage AC input. Figure 55 shows a boost converter topology including a pulse width modulation circuit 6202 (such as the Unitrode UC3845 circuit) for applying a pulse signal to a gate of switch transistor 6206. Components shown in Figure 55 may be sized to generate an output voltage at a range of about 100 to 300 volts DC. Figure 55 shows an alternative embodiment having a push-pull topology. Circuit 6302 is a square wave oscillator (such as the Unitrode UC1825 circuit) coupled to complementary output driving switch transistors 6304 and 6306. The transformer 6308 includes a primary coil tapped in three places. Switch transistors 6304 and 6306 apply complementary drive signals to separate taps in the primary coil of the transformer 6308 to drive the output voltage to be between about 100 to 300 volts DC. It is understood that the circuits shown in Figure 55 and 56 merely illustrate two possible topologies for the circuitry in the secondary adapter and that other topologies may be used for converting a low voltage DC signal to a high voltage input to a power adapter designed to receive a high voltage AC input. While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims: Claims What is claimed is: 1. In a system for providing DC power to a portable electronic appliance, the system including a primary power adapter having a power input terminal adapted for receiving an AC voltage within a set range and having a power output terminal to provide DC signal to meet an input power requirement of the portable electronic appliance, the improvement including a secondary power adapter comprising: a DC power input terminal adapted to receive a power signal from a DC power source at a set voltage range; and a power output terminal adapted to couple to the input power terminal of the primary power adapter to apply an intermediate power signal to the power input terminal of the primary power adapter within the set range, wherein the intermediate power signal applied to the input power terminal of the primary adapter causes the primary adapter to provide a power signal to meet the input power requirement of the portable electronic appliance. 2. The system of claim 1 , wherein the secondary power adapter further includes one of a boost regulator and a push-pull circuit. 3. The system of claim 1 , wherein the intermediate power signal is a DC power signal between 100 and 400 volts. 4. The system of claim 1 , wherein the power output terminal of the secondary adapter mates with the power input terminal of the primary power adapter. 5. The system of claim 1 , wherein the DC power input terminal of the secondary adapter is adapted to receive the power signal from the DC power source at a voltage of about twelve to fifteen volts. 6. The system of claim 1 , wherein the input power requirement of the portable electronic appliance is one of an operational voltage and an operational current. 7. The system of claim 1 , wherein the portable appliance is one of a portable telephone, a portable computer, a game system and a video device, and wherein the primary power adapter provides output power to the portable electronic appliance to meet one of an input voltage requirement and an input current requirement. 8. The system of claim 1, wherein the primary power adapter is programmable to supply the power signal to substantially meet an input current requirement of power requirement of either a portable telephone or a portable computer. 9. A method of providing power to a portable electronic appliance having an input power requirement, the method comprising: coupling a power output terminal of a primary power adapter to a power input terminal of the portable electronic appliance, the primary power adapter having a power input terminal adapted for receiving an AC voltage within a set range; coupling an output power terminal of a secondary power adapter to the power input terminal of the primary power adapter to provide an intermediate power signal; and coupling a DC power input terminal of the secondary power adapter to receive a power signal from a DC power source at a set voltage range, wherein the intermediate power signal applied to the input power terminal of the primary adapter causes the primary adapter to provide a power signal to meet the input power requirement of the portable electronic appliance. 10. The method of claim 9, the method further including generating the intermediate power signal from one of a boost regulator and a push-pull circuit. 11. The method of claim 9, wherein the intermediate power signal is a DC power signal between 100 and 400 volts. 12. The method of claim 9, the method further including mating the power output terminal of the secondary adapter with the power input terminal of the primary power adapter. 13. The method of claim 9, the method further including providing a DC voltage in a range of about twelve to fifteen volts to the DC power input terminal. 14. The method of claim 9, wherein the input power requirement of the portable electronic appliance is one of an operational voltage and an operational current. 15. The method of claim 9, wherein the portable appliance is one of a portable telephone, a portable computer, a game system and a video device, and wherein the primary power adapter provides output power to the portable electronic appliance to meet one of an input voltage requirement and an input current requirement. 16. The method of claim 15, wherein the primary power adapter is programmable to supply the power signal to substantially meet an input current requirement of power requirement of either a portable telephone or a portable computer. 17. A secondary power adapter, the secondary power adapter comprising: a DC power input terminal adapted to receive a power signal from a DC power source at a set voltage range; and a power output terminal adapted to couple to an input power terminal of a primary power adapter, primary power adapter having a power input terminal adapted for receiving an AC voltage within a set range and having a power output terminal to provide DC signal to meet an input power requirement of a portable electronic appliance, to apply an intermediate power signal to the input power terminal of the primary power adapter within the set range, wherem the intermediate power signal applied to the input power terminal of the primary adapter causes the primary adapter to provide a power signal to meet the input power requirement of the portable electronic appliance. 18. The secondary power adapter of claim 17, wherein the secondary power adapter further includes one of a boost regulator and a push-pull circuit. 19. The secondary power adapter of claim 17, wherein the intermediate power signal is a DC power signal between 100 and 400 volts. 20. The secondary power adapter of claim 17, wherein the power output terminal of the secondary adapter mates with the power input terminal of the primary power adapter. 21. The secondary power adapter of claim 17, wherein the DC power input terminal of the secondary adapter is adapted to receive the power signal from the DC power source at a voltage of about twelve to fifteen volts. 22. The secondary power adapter of claim 17, wherein the input power requirement of the portable electronic appliance is one of an operational voltage and an operational current. 23. The secondary power adapter of claim 17, wherein the portable appliance is one of a portable telephone, a portable computer, a game system and a video device, and wherein the primary power adapter provides output power to the portable electronic appliance to meet one of an input voltage requirement and an input current requirement. 24. The secondary power adapter of claim 22, wherein the primary power adapter is programmable to supply the power signal to substantially meet an input current requirement of power requirement of either a portable telephone or a portable computer.

Inventors: LANNI THOMAS W, LANNI, THOMAS, W.
Applicants: COMARCO WIRELESS TECHNOLOGIES, COMARCO WIRELESS TECHNOLOGIES, INC.
Application year: 2001
Main classification: H02M7
IPC codes: H02M3, H04M1