Patent Publication Number: US-6903950-B2

Title: Programmable power converter

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from and is a continuation-in-part of U.S. patent application Ser. No. 10/384,263 filed Mar. 7, 2003, now U.S. Pat. No. 6,791,853, which is a continuation-in-part of U.S. Ser. No. 10/225,933 filed Aug. 22, 2002, now U.S. Pat. No. 6,650,560, which is a continuation-in-part of U.S. patent application Ser. No. 10/159,910 filed May 31, 2002, now U.S. Pat. No. 6,751,109, which is a continuation-in-part of U.S. patent application Ser. No. 10/005,961 filed Dec. 3, 2001, now U.S. Pat. No. 6,643,158, and also is a continuation-in-part of U.S. patent application Ser. No. 10/072,074 filed Feb. 8, 2002, now U.S. Pat. No. 6,700,808, the teachings of which are incorporated herein by reference. In addition, this application claims priority of U.S. Provisional Application No. 60/484,344, filed on Jul. 2, 2003 titled “REMOTELY PROGRAMMABLE POWER CONVERTER”, filed by express mail number EV 329715761US, and incorporated herein by reference. 

   TECHNICAL FIELD OF THE INVENTION 
   The present invention generally relates to the field of power converters, and, more particularly, to programmable power converters. 
   BACKGROUND OF THE INVENTION 
   As the use of mobile electronic products continues to increase, such as PC notebooks, PDAs , cellular telephones, MP3 players and the like, the need for low cost, compact power supplies and solutions to power and recharge these products also continues to increase. Most manufacturers of mobile products typically provide plug-in power adapters along with these mobile products to help provide the power supply needs of their customers. 
   Today&#39;s power adapters are typically AC-to-DC, or DC-to-DC power converters which are configured to convert an AC voltage to a DC voltage, or step-up or step-down the DC voltage input delivered to the mobile device. With AC-to-DC adapters, for example, users can power most mobile devices by simply plugging the adapter into a standard AC wall outlet commonly found in most homes and offices. Similarly, when only DC input power is available, such as in an automobile or airplane, users can still power their mobile devices by simply using a standard, off-the-shelf DC-to-DC adapter, such as with a cigarette lighter connector. Normally, both adapters are designed and tailored to provide a regulated DC output voltage, which voltage typically ranges from between 5VDC to 30VDC depending on the power requirements of mobile device being powered. 
   Although these power adapters conveniently provide direct power and recharging capabilities, users are often required to carry separate adapters to provide power to each individual mobile device. This often means that users have to carry multiple adapters for each device: one for an AC input power source, and another for a DC input power source. Moreover, users with multiple devices are typically required to carry multiple adapters to power all the multiple devices, thereby increasing the amount of bulk a user is required to carry, which is also tedious. 
   Accordingly, there exists a need for a power converter and system that resolves the system power management problems associated with carrying all of the different power supply components necessary to power a wide variety of mobile and portable devices having different power requirements. Moreover, there is a need for a power converter and system that is programmable for providing power with selected electrical characteristics. 
   SUMMARY OF THE INVENTION 
   The present invention achieves technical advantages as a programmable converter supplying programmable DC voltages adapted to power a plurality of portable devices. In one embodiment of the invention, the converter receives a DC input signal or AC input signal, and provides a predetermined DC output signal, and includes circuitry responsive to the DC signal or AC input signal for providing a converted DC signal in which the converted DC signal has electrical characteristics which are selectable, and includes a controller cooperable with the circuitry for establishing the electrical characteristics based on a selection code. 
   In another embodiment, the converter includes a coupler coupled to the circuitry in which the programming circuitry includes a socket adapted to receive a insertable memory device and electrically couple the programming circuitry and the memory device. The memory device for storing a code indicative of an electrical characteristic selection, wherein the code is readable from the memory by the programming circuitry for imposing the electrical characteristic selection upon the converted DC signal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Advantages of the invention and the specific embodiments will be understood by those of ordinary skill in the art by reference to the following detailed description of preferred embodiments taken in conjunction with the drawings, in which: 
       FIG. 1A  shows a block diagram of a dual input AC and DC power converter having dual DC voltage outputs in accordance with the present invention; 
       FIG. 1B  shows an exploded view of the converter with the detachable buck circuit; 
       FIG. 2  shows a schematic diagram of the power converter circuit as illustrated in  FIG. 1  in accordance with the present invention; 
       FIG. 3  shows a detailed schematic diagram of a DC-to-DC buck converter circuit in accordance with the present invention; 
       FIG. 4  is a perspective view of a power converter system including a power converter adapted to receive both an AC and DC voltage input, and a peripheral power hub (PPH) according to the present invention; 
       FIG. 5  is an electrical block diagram of one preferred embodiment of the PPH shown in  FIG. 4 , where each of the outputs of the PPH are connectable to an associated selectively attachable buck circuit providing a selectable voltage to an associated remote device; 
       FIG. 6  is an electrical block diagram of another preferred embodiment whereby the PPH includes a plurality of programmable buck circuits, each having a selectively removable programming device, shown as a resister R 1 , whereby each remote mobile device can be directly coupled to a PPH output as shown; and 
       FIG. 7  illustrates a block diagram of a dual input AC and DC power converter having DC voltage outputs in accordance with exemplary embodiments of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The numerous innovative teachings of the present applications will be described with particular reference to the presently preferred exemplary embodiments. However, it should be understood that this class of embodiments provides only a few examples of the many advantageous uses and innovative teachings herein. In general, statements made in the specification of the present application do not necessarily delimit any of the various claimed inventions. Moreover, some statements may apply to some inventive features, but not to others. 
   There is shown in  FIG. 1A  a block diagram of a dual input AC/DC power converter  10  having dual programmable DC voltage outputs in accordance with the present invention. Preferably, the dual input AC/DC power converter  10  comprises a power converter circuit  20  having an AC-to-DC converter  22 , a DC-to-DC booster converter  24 , a feedback circuit  26 , a filter circuit  25  and a DC-to-DC buck converter  28 . The power converter circuit  20  is seen housed in housing  13  and advantageously provides a first programmable DC output voltage at DC output terminal  16  and a second programmable DC output voltage at terminal  18 . Both of these DC output voltages may be generated as a function of both AC and DC input voltages. 
   In operation, the AC-to-DC converter  22  receives an AC signal via input terminal  12  and provides a regulated DC output voltage at node N 1 . Similarly, the DC-to-DC booster converter  24  may receive a DC input voltage at its input via input terminal  14  and may also provide a regulated DC output voltage at node N 1 . 
   Input terminals  12  and  14  are integrated into a single common connector  17  such that different power cords adapted to receive input power from different sources are received by the common connector  17 . For instance, DC power from an airplane or car power source are wired to couple to input  14  and AC source is wired to couple to input  12 . In a selected embodiment, the AC-to-DC converter  22  is adapted to generate a DC output voltage of between 15VDC and 24VDC in response to an AC input voltage at terminal  12  ranging between 90VAC and 265VAC. Likewise, the DC-to-DC booster converter  24  is adapted to provide a DC output voltage which is substantially similar to that of converter  22 , but which is generated in response to a DC input voltage supplied at input terminal  14 . Preferably, DC-to-DC booster converter  24  is adapted to receive a voltage in the range of between 11VDC and 16VDC. Advantageously, AC-to-DC conversion, via AC-to-DC converter  22 , allows users of the power converter  10  to power high-power mobile devices, such as a laptop computer wherever AC input power is available, such as in the home or office, for example. Conversely, the DC-to-DC booster converter  24  of the power converter  10  is capable of powering similar high-power devices by stepping up most low amplitude DC input signals, such as those found in automobile and/or airplane environments. 
   As shown, filter circuit  25  has its input tied to the respective outputs of the converter  22  and  24 . In a preferred embodiment, the filter circuit is adapted to provide a filtered DC output voltage at second node N 2 , which, thereafter, feeds output terminal  16 , at an output power of 75 watts, for example. 
   The single feedback circuit  26  is shown coupled to the output of filter circuit  25  at node N 2 . In a preferred embodiment, the feedback  26  circuit, through a single feedback loop, regulates the voltage level of the filtered DC output voltages generated by both converters  22  and  24 . Additionally, the feedback circuit  26  is adapted to receive a removable programming module that allows mobile device users to provide a selectable DC output voltage at output  16  via node N 2 . The programming module comprises a key  15  comprising a resistor, wherein different associated values of the resistor establish different associated DC output voltages at output  16 . By allowing users to selectively change the voltage level of the filtered DC output voltage, the power converter  10  may be adapted to power a variety of different mobile electronic devices, having different associated power requirements. Moreover, the power converter&#39;s  10  programming module may also be adapted to provide the additional function of output current limiting. 
   The DC-to-DC buck converter  28  has its input coupled at node N 2 , providing a second DC output voltage that is then fed to output terminal  18 , having an output power of 10 watts, for example. Preferably, buck converter  28  discreetly steps down the filtered DC voltage and produces a second DC output voltage at a separate output terminal  18 . In a selected embodiment, the buck converter  28  steps down the filtered DC output voltage to a range of about 3VDC and 15VDC. Advantageously, this second DC output voltage generated by converter  28  is independent of, and substantially lower than the DC output voltage at terminal  16 . This allows users of the present invention to power not only a high-power peripheral, such as a laptop computer, but also, a second, low-power peripheral, such as a cell phone, PDA, and the like. Moreover, the present invention allows for these peripherals to be powered simultaneously by a single converter, regardless if the input voltage is AC or DC. The buck converter  28  is physically detachable from the main housing  13  as shown in  FIG. 1B , allowing different buck circuits providing different output voltages to be selectively attached to housing  13  and tap the DC output voltage from output terminal  18 . 
   Referring now to  FIG. 2  there is shown a schematic diagram of the power converter circuit  20  of the dual input AC/DC power converter  10  as depicted in  FIG. 1  in accordance with an exemplary embodiment of the present invention. As described herein in greater detail, the power converter circuit  20 , in a preferred embodiment, comprises three separate converters: AC-to-DC power converter  22 , DC/DC boost converter  24 , and DC-to-DC buck converter  28 . 
   AC-to-DC Converter 
   The AC-to-DC power converter  22  includes a true off line switcher which is configured in a fly-back topology. Full-wave rectification of an AC input signal, received at input terminal  12 , occurs using a full-wave bridge rectifier BD 1  and a filter capacitor C 1 , which creates a DC voltage bus from which the switcher operates. Inductor L 1  offers additional EMI filtering of the AC signal after the signal has been rectified through the full-wave bridge. The AC-to-DC converter  22  also includes a main controller IC 1  configured as a current mode pulse-width modulator (PWM). Main controller IC 1  is also configured to have a single-ended output with totem pole driver transistors coupled thereto. The AC-to-DC power converter  22  has a main power switch Q 7  which drives the main transformer T 1 . In a preferred embodiment, the transformer T 1 , Schottky diode D 11 , and filter capacitors C 24  and C 25  combine to provide the DC output voltage at node N 1 . 
   As noted earlier, filter circuit  25  allows for additional filtering of the DC output voltage derived from node N 1 . The filter circuit  25  itself comprises inductor L 3 , capacitor C 26  and transformer NF 1 . Advantageously, the filter circuit  25  produces a filtered DC output voltage at output  16  having less than 100 mv peak-to-peak noise and ripple. 
   The feedback circuit  26 , through a single feedback loop, is capable of regulating the filtered DC output voltages provided by the converters  22  and  24 . The feedback circuit  26  is also adapted to be coupled to a removable programming module having a key  15 , comprising resistor R 53 . As such, the present invention allows users to selectively program the DC output voltage later received at output terminal  16 . The feedback circuit  26  includes a photocoupler circuit comprising a pair of photocouplers PH 1  and PH 3  connected in series (i.e., stacked), each being coupled to the outputs of operational amplifiers IC4-A and IC4-B. Advantageously, these photocouplers are arranged along the feedback loop of the feedback circuit  26  with photocoupler PH 1  and PH 3  coupled respectively to converters  22  and  24 . Through a single feedback loop, the feedback circuit  26  efficiently regulates the filtered DC output voltage provided at node N 2 . Moreover, by stacking the photo-couplers, the present invention also allows the power converter  10  to maintain proper input/output isolation between respective terminals  12  and  14  and output terminal  16 . 
   Preferably, the output current limiting function of converter  22  is accomplished via integrated circuit IC 4 A, resistors R 33 , R 37 , R 38 , and R 39  and programming resistor R 54 . 
   Over voltage protection of AC-to-DC converter  22  is achieved using photocoupler PH 2  and zener diode ZD 2 . In a preferred embodiment, zener diode ZD 2  is set at 25V such that when in avalanche mode it causes the transistor side of photocoupler PH 2  to bias transistor Q 1  into the on state. When it is the on state, transistor Q 3  pulls low pin  1  of integrated controller IC 1  and pulls the operating duty cycle of the integrated controller towards 0%. This takes the DC output voltage to 0 volts. Also, when transistor Q 1  is on, transistor Q 2  is also forced on which then forces these two transistors become latched. If transistors Q 1  and Q 2  are latched, input power must be recycled in order for the power converter  10  to be turned on again. 
   DC-to-DC Converter 
   The DC-to-DC converter  24  is configured in a boost topology and utilizes the same kind of integrated controller, IC 2 , as used in converter  22 . In the DC-to-DC converter  24 , transistor Q 8  acts as the main power switch and diode D 8  as the main rectifier. Preferably, inductor L 2  is adapted to function as a power boost inductor, which is comprised of a toroid core-type inductor. It should be understood that the cathode leads of diodes D 11  and D 8  are connected, forming an ORed configuration, requiring only one output filter. Advantageously, this eliminates the board space needed for a second set of filter capacitors. 
   Like the AC-to-DC converter  22 , the DC-to-DC converter  24  is also designed to operate at a frequency of around 80 KHZ. For the AC-to-DC converter  22 , the operating frequency is set by resistor R 13  and capacitor C 7 . Likewise, the operating frequency of the DC-to-DC converter  24  are set by resistor R 28  and capacitor C 16 . 
   The DC-to-DC converter  24  includes an over-voltage protection circuit comprising zener diode ZD 2 , resistor R 23 , R 24 , R 48 , transistor Q 4 , and silicon-controlled rectifier SC 1 . Zener diode ZD 2  sets the over-voltage protection point (OVP) which is preferably set at 25VDC. Generally, there is no current flowing through resistor R 48 . If, however, when zener diode ZD 2  begins to conduct current, the drop across R 48  is significant enough to bias transistor Q 4  on, pulling its collector terminal high, and thereby turning silicon controlled rectifier SC 1  on. When silicon control rectifier SC 1  is on, it pulls pin  1  of the integrated controller IC 2  low. Thus, if pin  1  of integrated controller IC 2  is low, the output drivers thereof are forced to operate at a duty cycle of 0%, thereby producing a DC output voltage of 0 volts at IC 2  pin  6 . Advantageously, the silicon controlled rectifier SC 1  functions as a power latch circuit that requires that input power be recycled in order to turn on the power converter  10  if a voltage above 25VDC is detected at node N 1 . 
   The temperature of the housing  13  of the power converter  10  is monitored using a thermistor NTC 3 . If, for example, there is a corresponding increase in the temperature of the housing  13 , it will result in a decrease in the resistive value of thermistor NTC 3 , thereby causing transistor Q 9  to turn on and pull low pin l of integrated circuit IC 2  of converter  24 . Moreover, this causes the photo-coupler PH 2  to be biased enough to activate a latch circuit comprising transistors Q 1  and Q 2  that will shutdown the power converter  22 . In addition, the power converter&#39;s  10  thermal protection feature is adapted to operate regardless of whether an AC or DC input voltage is being received at their respective input terminals. 
     FIG. 3  shows a detailed schematic diagram of the DC-to-DC buck converter  28  in accordance with the present invention. The buck converter  28  has an integrated circuit controller IC 1 , similar to converters  22  and  24 , which is adapted to generate an on-time duty cycle to power transistor switch Q 1 . The operating frequency of controller IC 1  is set by capacitor C 6 , which is coupled between pin  4  of IC 1  and ground, and resistor R 1 , which is coupled between pins  4  and  8 . In a selected embodiment, the diode D 1  functions comprises a Schottky diode and functions as “catch” diode. Inductor L 1  is a output power inductor and couples the source of power transistor Q 1  to V out . Fuse F 1  is shown coupled between V in  and the drain terminal of power transistor Q 1 , and advantageously provides current protection to buck-converter  28 . 
   Furthermore, the input V in  of the buck converter  28  is coupled to the output of filter circuit  25  at node N 2 , wherein V in  receives the filtered DC output voltage therefrom. In a preferred embodiment, the buck converter  28  provides a second DC output voltage at V out , coupled to output terminal  18 . Advantageously, the buck convert  28  discreetly steps down the filtered DC output voltage and provides a second DC output voltage at output terminal  18  which is independent of, and substantially lower than the DC output voltage at output terminal  16 . Likewise, the DC output voltage of the buck converter  28  enables users of the present invention to power low-power peripherals, such as, cell phones, PDAs, and/or similar mobile devices. In a selected embodiment, the buck converter  28  may also be adapted to provide a DC output voltage at output terminal  18  ranging between 3VDC and 15VDC, selectively determined as a function of the chosen value of resistor R 2  used in the particular buck converter  28 , with a total power delivery of 10 watts, for example. As previously mentioned, the buck converter  28  may be housed in a separate, detachable program module that enables users to selectively program the DC output voltage at terminal  18  as a function of different associated buck converter modules. 
   Referring now to  FIG. 4 , there is generally shown at  40  a perspective view of a peripheral power system (PPS) seen to include the AC/DC-to-programmable DC output converter  42  as shown and described in reference to  FIGS. 1-3 . In addition, PPS  40  is also seen to include a peripheral power hub (PPH) shown at  44  and having a plurality of DC voltage outputs generally shown at  46 . As will be described in more detail shortly, in one preferred embodiment ( FIG. 5 ) predetermined DC voltages are provided at each output which may then be converted by a buck circuit  28  associated with the peripheral device  72  to be powered. In another preferred embodiment ( FIG. 6 ) each of these outputs  46  is programmable as a function of a removable programming key, such as a selectively replaceable programming resistor. Converter  42  provides a predetermined output DC voltage, which may be programmable, via a DC voltage coupler  48  to a primary device, such as a notebook computer  50 , requiring a higher operating voltage and consuming a large amount of power, such as  45  watts. DC voltage coupler  48  also provides tapping of this output DC voltage provided to the primary device  50 , which voltage is tapped via a connector  52 . 
   In the embodiment shown at  60  in  FIG. 5 , the input voltage provided to input  62  is muxed to the plurality of output ports  46 . The separate buck circuits  28  associated with and selectively coupled to the associated remote mobile device  72  convert this voltage to the final output voltages V 1 -V 4  as shown in  FIG. 5 , which meets all the power needs of the associated mobile device  72 . According to the embodiment shown at  70  in  FIG. 6 , the plurality of buck circuits  28  are integral to the PPH  44 , each buck circuit  28  having a selectively removable programming key, shown as resistor R 1 , providing a programmable DC voltage to the respective output port  46  commensurate with the requirements of the associated remote mobile  72  device. Output ports  46  may be configured as simple pin type connectors, USB type connectors, and other configurations as desired. Again, the buck circuit  28  could be substituted with a boost circuit if desired to provide a higher voltage. 
   Turning now to  FIG. 5 , there is shown the first embodiment of the present invention comprising the PPH  44  shown in FIG.  4 . As previously mentioned, the input DC voltage provided to the PPH  44  at input  62  is coupled to each of the output ports  46  by a voltage mux  64 . This coupling of the input DC voltage to the multiple output ports  46  can be accomplished in a number of ways, such as via a simple resistive divide network, and may provide output-to-output isolation. In one implementation, the DC voltage provided at input  62  is directly provided to the output ports  46  for a subsequent down-stepping via the associated buck circuit  28 . However, a lower voltage can be provided by the voltage mux  64  to each of the output ports  46  if desired. Voltage mux  64  is also seen to include an over load protection circuit generally shown at  66  which limits the amount of power that can be provided to each output port  46 , such as 7 watts, to prevent overload of the PPH  44 , and to prevent power hoarding at one output by its associated remote device  72  to the determent of the other remote devices  72 . 
   Visual indicators  68  are provided to visually indicate the status of each output port  46 . For instance, the LED  68  associated with each of the output  46  may be illuminated as green when power provided via output port  46  is below a predetermined limit, such as 7 watts each. If, however, a remote device  72  associated with the particular buck circuit  28  is attempting to draw more than the predetermined limit, the voltage mux  64  prevents providing power in excess of this predetermined limit, and also illuminates the associated LED as red indicating an attempted over power condition. Thus, a user can visually ascertain whether or not power being provided to the associated output port  46  is within an acceptable range as visually indicated by an associated green LED  68 , or, that the associated remote device  72  is attempting to draw more than the predetermined limit. The voltage mux  64  also includes a main fuse  69  preventing excessive power draw of the PPH  44  itself, which could otherwise cause an overload condition to the power converter  42  or other input power source. 
   The advantages of the embodiment  60  shown in  FIG. 5  include that a separate buck circuit  28  and the associated cord can be simply coupled to any of the output ports  46  and provide a programmable DC output voltage meeting ther needs of the associated remote device  72 . A user having a buck circuit  28 /cord for use with the particular remote device  72  can be plugged into any of the available output ports  46  of the PPH  44 . The DC voltage is stepped down by buck circuit  28  external to the housing of PPH  44 . This solution is low cost and a simple design. 
   Turning now to  FIG. 6 , there is shown at  70  another preferred embodiment of the present invention whereby a plurality of buck circuits  28  are provided within the PPH  44  to provide a programmable output DC voltage to the respective output port  46 . Each buck circuit  28 , as shown in  FIG. 3 , has an associated programming resister R 1  which may be selectively removable from the PPH  44  to selectively establish the output DC voltage provided to the associated output port  46 . Thus, the DC output voltage at each output port  46  is selectively programmable, and a remote device  72  need to only utilize a standard two conductor cord to couple to output port  46 , as shown. Namely, one conductor couples the programmable output voltage V 1 , and the other conductor provides the ground. Again, each buck circuit  28  could be substituted with a boost circuit if desired. 
   Advantages of this embodiment  70  include that the buck circuits  28  are enclosed in the PPH  44 , where each buck circuit  28  itself may be programmable using the associated programming resistor R 1 . In this arrangement, care must be taken that the remote device  72  is coupled to an output port having a desirable output voltage. Thus, the keys provide indicia of the output voltage being provided. The voltage mux  64  simply provides the input voltage at input  62  to each of the buck circuits  28 , which may step down (or step up) the voltage thereat. Voltage mux  64  includes the overload protection circuit  66 , the associated LED&#39;s  68 , and the hub main fuse  69  as shown. 
   Both embodiments  60  and  70  provide a DC peripheral power hub adapted to power a plurality of unique remote devices  72  from a single unit  44 , such remote devices including a cell phone, PDA, MP3 player, etc. This peripheral power hub  44  may be an accessory to power converter  42 , or, a stand alone device receiving power. For instance, the input cord  52  feeding PPH  44  may be directly coupled to an output of converter  42 , as shown in  FIG. 4 , tapped from the DC coupler  48  without any down stepping by a buck circuit  28 , or directly coupled to a DC source, such as via a cigarette lighter outlet, or other input source. 
   According to yet another preferred embodiment, as shown in  FIG. 7 , the power converter  10  include programming circuitry  726 , such as a micro-controller (computer chip). The programming circuitry  726  is cooperable with converters  22  and  24 , and filter  25  for effectuating a program for setting the electrical parameters associated with the output signals  16  and/or  18 , such as the output voltage, output current, output power, current limit, polarity, over voltage protection threshold, and/or other electrical parameters associated with each of the output signals  16  and  18 . Programming signaling/feedback occurs through communication lines  722  and  724 . For example, the converter  10  with a micro controller inside, adjusts the numerical value of sensing resistor(s) or reference voltage(s) (shown in  FIGS. 2 and 3 ) to effectuate a determined output voltage(s), output current(s) or output power. The programming circuitry  726  can include memory  715  for data and program storage, hardware, and/or software which enables start-up and control for effectuating the above-mentioned electrical properties. In a preferred embodiment, the programming circuitry  726  is powered from the converted signal of either converters  22  or  24 . 
   Data indicative of electrical parameter selection is storable by the programming circuitry  726  in memory  715 , such that on a power-up condition the data is read and the associated electrical parameters of the signal output  16  and/or  18  are effectuated by the programming circuitry  726 . This data can be programmed into the programming circuitry  726  and subsequently into the memory  715  from outside the power supply unit. That way, by changing the data that is provided to the programming circuitry  715  and memory, the characteristics of the supplied signal can be changed at will. For example, the data can be provided to the programming circuitry  726  at the time of production or by an OEM vendor who might stock standard power supply units and then program each one for a specific customer&#39;s needs. This process would be akin to activating a new cell phone with the customer&#39;s information. The data can also be provided by the peripheral device  72  to be powered, such that the device  72  programs the programming circuitry  715  to effectuate electrical parameters required for the device  72 . 
   The data can be provided from a source  710  external to the converter  10  (such as a program controller) via a simple  2  pin connector, infra-red or visible optical signaling, magnetic induction, acoustic signaling, etcetera. Transmission mediums  725  for communication between the external source  710  and the converter  10  include both wired mediums (such as coaxial cable, twisted pair wire, fiber-optic cable) and wireless mediums. The converter  10  can also include an interface  720  for interfacing between the different signaling types and transmission mediums, and the programming circuitry  715 . Thus, as can be understood, the converter  10  can be programmed via communication systems such as the Internet to deliver data, analog and/or digital, from an external source to the converter  10 . 
   In yet another exemplary embodiment, the programming circuitry  726  includes an EPROM  715  which forms a portion of the circuitry. The EPROM  715  can be permanently affixed in the converter  10  or selectively insertable into, and removable from an EPROM socket (i.e., keyway). The EPROM is programmed external of the converter  10  (using an EPROM burner, for example), and then inserted into the socket to effect the desired output characteristics. Advantageously, the EPROM chip could be programmed at the time of purchase, and then installed by a salesman into the converter. Advantageously, several EPROM chips can each be programmed for different output characteristics and selected from and inserted as the intended use changes. An EEPROM may also be utilized in place of the EPROM to prevent the need to install different EPROMS for different output programming. 
   Though the invention has been described with respect to specific preferred embodiments, many variations and modifications will become apparent to those skilled in the art upon reading the present application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.