Patent Publication Number: US-7721213-B2

Title: Graphical interface for configuring a power supply controller

Description:
REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 10/621,414, entitled “GRAPHICAL INTERFACE FOR CONFIGURING A POWER SUPPLY CONTROLLER”, and filed on Jul. 18, 2003. 
     Reference is directed to the following United States patents, the entire disclosure of each of which is hereby incorporated herein by reference: 
     “Power Supply Controller”, R. Orr et al., application Ser. No. 10/428,095 filed May 2, 2003, now U.S. Pat. No. 6,850,048; 
     “Sequencing Power Supplies”, D. Brown et al., application Ser. No. 10/428,105 filed May 2, 2003, now U.S. Pat. No. 6,879,139; 
     “Sequencing Power Supplies On Daughter Boards”, D. Brown et al., application Ser. No. 10/428,136 filed May 2, 2003, now U.S. Pat. No. 7,080,273. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a graphical interface for use in configuring a power supply controller, in particular a power supply controller that can be used for controlling a plurality of power supplies. The term “power supply” is used herein to refer to any type of device for supplying controlled electrical power for a load. For example, the power supplies may comprise isolating and/or non-isolating switch mode power supplies or DC power converters, voltage regulator modules, and linear voltage regulators. 
     BACKGROUND 
     The related applications describe and claim aspects of a power supply controller which can be used for controlling a plurality of isolating and/or non-isolating power supplies, such as switch mode power supplies or DC power converters, and linear voltage regulators, for providing controlled electrical power to loads. For example, the power supplies may provide different supply voltages to various electrical circuits on a circuit card on which the power supply controller is also provided. As described in the related applications, the power supply controller has six converter state machines (CSMs), one for each of up to six controlled power supplies, and an input state machine (ISM) for an input or supply voltage for the controlled power supplies. 
     A primary aspect of the control of the power supplies relates to their sequencing in accordance with conditions monitored by the power supply controller. Sequencing refers to an order in which, and parameters in dependence upon which, the power supplies are enabled or started up in a power-up process, disabled or shut down in a normal power-down process, and/or disabled or shut-down in a fault situation. The monitored conditions include, for example, the input voltage and the output voltages produced by the respective power supplies. For example, enabling of each individual controlled power supply on power-up of the circuit card can be dependent upon the input voltage, or upon a monitored output voltage of a prior-enabled power supply, exceeding a threshold voltage. 
     The related applications by D. Brown et al. disclose arrangements of controlled power supplies that can provide relatively arbitrary sequence topologies, and that allow for a location of each controlled power supply on either a main circuit board or a daughter board. As described in these applications, various configuration registers are provided in the power supply controller to identify the presence and locations of the controlled power supplies and their sequencing for power-up, normal shut-down, and shut-down in a fault situation. 
     In addition to this information, it is desirable to be able to vary, and it is therefore necessary to specify for desired operation of the power supply controller, a large amount of other configuration information relating to the controlled power supplies and their sequencing. 
     By way of example, such other information can include, for each controlled power supply, under- and over-voltage thresholds and associated time periods for triggering warnings and detecting fault conditions in operation of the controlled power supply, a mask time period for start-up to be completed before under-voltage monitoring takes effect, a start-up voltage threshold which must be exceeded to trigger a subsequent CSM in the power-up sequence of the controlled power supplies, a restart voltage threshold below which the monitored voltage must fall before a power-up sequence is initiated following a shut-down of the controlled power supplies, voltage parameters for adjustment or trimming of the controlled power supply output voltages, and time delay periods associated with the power-up, normal shut-down, and fault shut-down sequences. 
     Such other information can further include a threshold voltage and related period which must be exceeded by the input voltage for a power-up sequence of the controlled power supplies to begin, and information related to the use of general purpose input/output (GPIO) pins of the power supply controller. 
     All of this and any other desired information for operation of the power supply controller, collectively referred to herein as configuration information, must be correctly set up for operation of the power supply controller. For example, the configuration information is stored in a non-volatile random access memory (NVRAM) of the power supply controller, and is downloaded from the NVRAM to registers of the power supply controller on power-up of the power supply controller. 
     While such a power supply controller is very versatile, it can be seen that its configuration information is relatively complex. Voltage thresholds and time delays such as those identified above, especially those relating to power supply sequencing for power-up and shut-down, must be correctly set for operation of the power system; if even one of the registers for this configuration information is set incorrectly the power system may be rendered inoperable. Furthermore, the configuration of the power supply controller may be by power system designers who have previously used only analog power system control circuits and who are not familiar with a configurable power supply controller such as described above. 
     Accordingly, there is a need to facilitate such configuration of a power supply controller. 
     SUMMARY OF THE INVENTION 
     According to one aspect of this invention there is provided a graphical interface method for producing configuration information for control apparatus for a power system including a plurality of power supplies, comprising the steps of, using a processor: receiving information relating to characteristics and connections of the plurality of power supplies, said information determining a topology of the power system; displaying on a display device a graphical display representing the topology of the power system; receiving user input information to determine sequencing of the plurality of power supplies; displaying on the display device a graphical display representing the sequencing of the plurality of power supplies; and producing said configuration information for the control apparatus consistent with the displayed topology and sequencing of the plurality of power supplies. 
     The step of receiving said information determining a topology of the power system preferably comprises receiving user input information for identifying information for at least one of the plurality of power supplies in a database. In this case the step of producing said configuration information conveniently comprises deriving information for said at least one of the plurality of power supplies from the database. 
     Preferably the step of displaying a graphical display representing the topology of the power system comprises displaying icons representing the plurality of power supplies and paths extending to and from the icons representing input and output voltage lines of the power supplies. 
     The step of displaying a graphical display representing the sequencing of the plurality of power supplies can comprise displaying at least some of said icons representing the plurality of power supplies in relatively different positions along respective ones of said paths, and/or displaying at least one additional symbol, such as an arrow and/or a sequence number, representing said sequencing. 
     The step of receiving user input information to determine sequencing of the plurality of power supplies preferably comprises the steps of displaying options for possible sequencing of each of the plurality of power supplies after another of the plurality of power supplies, and determining sequencing in response to user input selection of said options. Conveniently, a matrix is displayed having different representations for selected, selectable, and non-selectable sequencing options. 
     Preferably the graphical display representing the sequencing of the plurality of power supplies represents startup sequencing of the power supplies, and the step of producing said configuration information for the control apparatus comprises producing said configuration information for startup sequencing of the power supplies consistent with the displayed sequencing and for normal shutdown of the power supplies with sequencing reversed from the startup sequencing. 
     Desirably, different types of power supply, e.g. isolating or non-isolating, switch mode and linear, power supply types, are represented by different icons. 
     The invention also provides a method of configuring control apparatus for a power system including a plurality of power supplies, comprising the steps of producing configuration information for the control apparatus using the method recited above, and transferring the configuration information to the control apparatus. 
     Another aspect of the invention provides a graphical interface method for producing configuration information for control apparatus for a power system including a plurality of power supplies, comprising the steps of, using a processor: in response to user input, displaying on a display device a graphical display representing the topology and sequencing of the plurality of power supplies of the power system; and producing said configuration information for the control apparatus consistent with the displayed topology and sequencing of the plurality of power supplies. 
     A further aspect of the invention provides a graphical interface method for producing configuration information for control apparatus for a power system including a plurality of power supplies, comprising the steps of, using a processor: in response to user input, selecting power supplies using a database; in response to user input, determining sequencing of the power supplies; displaying on a display device a graphical display representing the power supplies and their sequencing; and producing said configuration information for the control apparatus consistent with the displayed sequencing of the power supplies and using information from the database for the selected power supplies. 
     The invention also provides a computer readable storage medium having software stored thereon for instructing a processor to implement any of the methods recited above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be further understood from the following description by way of example with reference to the accompanying drawings, in which: 
         FIG. 1  shows a block diagram of one example of a power supply system including a power supply controller and a plurality of controlled power supplies; 
         FIG. 2  illustrates an example of sequencing of controlled power supplies; 
         FIGS. 3 to 6  illustrate a graphical interface for configuring a power supply controller in accordance with an embodiment of this invention, these figures showing stages in defining a topology of a power supply system; 
         FIGS. 7 to 10  illustrate the graphical interface, showing stages in defining sequencing of the controlled power supplies of the power supply system having the topology shown in  FIGS. 1 and 6 ; 
         FIG. 11  illustrates the graphical interface, showing a different sequencing of the controlled power supplies of the power supply system having the topology shown in  FIGS. 1 and 6 ; 
         FIG. 12  illustrates a block diagram of a computer, providing the graphical interface, and an associated power supply controller; and 
         FIG. 13  illustrates configuration information for the power supply controller corresponding to the sequencing of controlled power supplies as shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a power system is illustrated by way of example as including six power supplies or converters  10  to  15 , an input voltage conditioning unit  16 , and a power supply controller  17 , all of which for example may be provided on a circuit card which, when inserted in an electrical equipment slot, is connected to an input power supply voltage Vin of for example 48 volts which serves as a power source for the entire card. The controller  17  then controls the power supplies  10  to  15  for producing respective supply voltages on rails V 0  to V 5  for electrical circuits on the circuit card. This control includes monitoring of the input voltage Vin and the output voltages of the controlled power supplies  10  to  15 , and sequencing of the power supplies on power-up, normal shut-down, and fault shut-down, for example as described in the related patent applications referred to above. 
     A power system can have any number of controlled power supplies or converters, and these can have a variety of different forms and can be connected to receive their respective source voltages in accordance with any desired topology. In the example of  FIG. 1 , each of the power supplies or converters  10 ,  11 , and  15  is an isolating switch mode power supply (SMPS), also referred to as a DC or DC-to-DC converter or a brick, whose source voltage is the input voltage Vin conditioned by the unit  16 . Further, each of the other power supplies or converters  12  to  15  is a non-isolating power supply whose source voltage is constituted by the output of the power supply or converter  11  on the rail V 1 . Each of the power supplies  12  and  13  is a non-isolating switch mode power supply or converter also referred to as a voltage regulator module (VRM). The power supply  14  is a non-isolating linear voltage regulator, which typically has a low drop out voltage and accordingly is also referred to as an LDO. 
     For convenience, this power system arrangement and topology as described above and illustrated in  FIG. 1  is adopted throughout this description, but it can be appreciated that the power system can have any desired arrangement and topology, including any desired numbers of input voltages, power supplies, and output voltages. 
     Although the power system topology may impose constraints on the sequencing of the controlled power supplies (for example in the power system topology of  FIG. 1  it is apparent that the power supplies  12  to  14  can not be powered up before power-up of the power supply  11  from which they derive their input voltages), the sequencing of the controlled power supplies is otherwise independent of the power system topology. Thus, for example, in the power system of  FIG. 1  the power supplies or converters  10 ,  11 , and  15  can be controlled by the controller  17  to be powered up simultaneously or in any desired sequence relative to one another. 
       FIG. 2  is a graph of output voltage as a function of time, illustrating one example of a power-up sequence of the controlled power supplies  10 ,  11 , and  12  of  FIG. 1  to produce their respective output voltages V 0 , V 1 , and V 2  under the control of the power supply controller  17 . Lines  20 ,  21 , and  22  in  FIG. 2  represent the respective output voltages of the controlled power supplies during this power-up sequence. 
     As shown in  FIG. 2 , the controller  17  initially (for example on determining that the input voltage Vin has exceeded a specified threshold voltage for a specified time period) enables the power supply  10 , and its output voltage rises as shown by the line  20 . When this output voltage exceeds a specified voltage threshold VT 0 , a start-up delay timer for the power supply  11 , which is specified as being next in this power-up sequence, is started to time a specified period T 1 , on the expiry of which the controller  17  enables this power supply  11  so that its output voltage rises as shown by the line  21 . When this output voltage exceeds a specified voltage threshold VT 1 , a start-up delay timer for the power supply  12 , which is specified as being next in this power-up sequence, is started to time a specified period T 2 , on the expiry of which the controller  17  enables this power supply  12  so that its output voltage rises as shown by the line  22 . 
     The voltage thresholds VT 0 , VT 1 , periods T 1 , T 2 , and the specified sequence are examples of extensive configuration information with which, as discussed in the Background above where further examples are also given, the controller  17  must be loaded for proper control and operation of the power system. When all of this configuration information has been determined for a particular type of power system, it can be simply loaded into the NVRAM of the controller  17 . However, determining all of the configuration information accurately and appropriately during a design phase of a power system can present a considerable difficulty for power system designers. 
     This difficulty is substantially reduced, and the design of a power system using a configurable power supply controller such as the controller  17  in  FIG. 1  is considerably facilitated, by the use of a graphical interface in accordance with this invention. By way of example, a graphical interface in accordance with one particular embodiment of the invention is described below with reference to  FIGS. 3 to 11  of the drawings. As indicated above, the illustrations in these figures relate to the particular power system topology described above with reference to  FIG. 1 , and it can be appreciated that the graphical interface is applicable to arbitrary topologies. 
     As will be appreciated, the graphical interface is conveniently provided on a display screen of a computer, and the computer conveniently provides not only management of the graphical interface as described below, but also features such as checking to avoid errors in the design of the power system and its operation, automatic establishment of appropriate parameters from a database of power supplies or converters which may be used in the power system, automatic setup of default values for other parameters, facilities to display and for a sophisticated designer to adjust any of the configuration information, and downloading of the resulting configuration information from memory or other storage in the computer, for example for evaluation of the configured power system using an evaluation board. 
     Each of  FIGS. 3 to 6  represents a “Topology” display, and each of  FIGS. 7 to 11  represents a “Sequence” display, of the graphical interface which are selected by respective tabs shown in these figures at the top of each display. Other tabs shown in  FIGS. 3 to 11  provide other displays which are not illustrated here. By way of example, as illustrated in  FIGS. 3 to 11  a “File Information” tab is provided to select a display for files relating to a particular power system; “Parameters”, “GPIO”, and “Advanced” tabs are provided to select displays for showing configuration parameters, setting parameters related to GPIO pins of the controller  17 , and adjusting any of the configuration information; an “Evaluation Board” tab is provided to select a display and function for downloading the configuration information to an evaluation power system; and “Margining” and “Monitoring” tabs are provided to select displays for showing and adjusting information related to margining and monitoring of the output voltages of the controlled power supplies. 
     As shown in each of  FIGS. 3 to 6 , the Topology display comprises a graphical panel  30 , an upper panel  31  above the panel  30 , and a lower panel  32  below the panel  30 , the lower panel being divided horizontally into four sections identified as “Details of Converter”, “Details of Rail”, “Margining”, and “Monitoring”. For simplicity and clarity, the Monitoring section is illustrated as being blank in each of  FIGS. 3 to 6 , but may include monitoring information for a power supply or converter highlighted in the panel  30  as described below. The upper panel  31  contains a database window  33 , a find window  34 , selection buttons  35  and  36 , and a caption  37 . 
     The computer stores in a database information relating to power supplies or converters that may be used in a power system, and information relating to a few of these is displayed in the database window  33 , which may be a scrollable window in known manner. For example,  FIGS. 3 to 6  illustrate the displayed information as including a model identifier, nominal output voltage, maximum load current, type (brick, VRM, or LDO as discussed above), and package information for each of six power supplies or converters in the database. Other information can similarly be displayed in the database window  33 . The information stored in the database for each power supply or converter also includes parameters constituting other parts of the configuration information required by the controller  17  in conjunction with use of the particular converter in a power system. For example, these parameters include preferred or default values for the various threshold voltages and associated time periods discussed above, such as the start-up voltage threshold, under- and over-voltage thresholds, etc. discussed above. This default or preferred configuration information can optionally be displayed (by horizontal scrolling) in the database window  33 , but this is not necessary because this information can instead be displayed by selecting other tabs (e.g. the Parameters tab). 
     The find window  34  is used in known manner to enter selection criteria, for example for output voltage, maximum output current, and/or make of converter, for finding desired converters in the database, for display of their relevant information in the database window  33 . Selecting the button  35 , labelled “New custom”, opens a window that enables information for a power supply or converter to be entered and added to the database in known manner. 
     Within the graphical panel  30 , supply voltage lines are represented by horizontal and vertical lines, and power supplies or converters are represented by icons to and from which horizontal supply voltage lines extend. The Topology display is used to construct a power system design with a desired arrangement and topology as described below. By way of example, the supply voltage lines are normally displayed as black lines, and a highlighted supply voltage line is displayed as a bright blue line. Similarly, different colours are desirably used in the panel for the icons for different types of power supply or converter, for example a brick or red-brown colour for a brick or isolating SMPS, blue for a VRM or non-isolating power supply or converter, and green for an LDO. These normal colours are conveniently lightened to highlight a selected converter. These different colours considerably enhance visible distinctions among the icons displayed in the panel  30 , but are not shown in the figures. In the figures, highlighted icons and supply voltage lines are shown by bold outlines and lines. 
     In addition, different types of power supply or converter are represented in the panel  30  by different icon displays, as further described below. 
     Initially, on selecting the Topology tab for a new power system design, the Topology display appears as shown in  FIG. 3 , with only an input voltage line shown and highlighted at the top left of the panel  30 . This line is labelled “Input” and its nominal voltage (e.g. 48V) is represented adjacent the line. This is a default voltage, which for example can be changed by selecting this voltage to display a change window. It is observed that as described here there is only one input voltage source; alternatively a power system can include two or more input voltage sources, and each additional input voltage source can be added to the Topology display in the panel  30  in any desired manner. 
     In  FIG. 3  the caption  37  reads “Power converters to add to Input”, as there is no other voltage line to which a converter can be added. No information (other than a default location of a converter on a main board) is displayed in the lower panel  32 . 
     A power supply or converter can be added to the input voltage line in the panel by selecting the converter in the database window  33  and selecting the button  36 , labelled “Add to rail”, to produce a Topology display for example as shown in  FIG. 4 , in which the added converter has been selected to highlight it and its output voltage line. As shown in  FIG. 4 , in the panel  30  the added converter has the adjacent label PC 0  (power converter zero) and produces its output voltage on a line labelled Rail V 0 , the nominal output voltage and maximum load current being shown adjacent the line representing this rail. Because this converter and its output voltage rail are highlighted, related information derived from the database is also shown in the sections of the lower panel  32 , and the caption  37  in the panel  31  now reads “Power converters to add to Rail V 0 ”. 
     The added power converter PC 0 , information for which is highlighted (shown by a bold outline) in the database window  33 , is an isolating SMPS or brick; this is represented in the panel  30  by the icon for this converter containing the word “Brick” and illustrating a transformer to represent the isolation between its input and output (in addition to the icon colour as described above). 
     At the bottom left of the lower panel  32 , buttons labelled “Move” and “Delete” enable a power converter and its output voltage rail, highlighted in the panel  30 , to be moved (where this is possible) or deleted. It can be appreciated that instead of, or in addition to, these and other functions as described here, the graphical interface may provide any other desired ways for changing the displayed power system topology. In particular, it is observed that these ways may include menu selections, keyboard operations, and/or so-called “drag-and-drop” functions using a computer mouse or other pointing and selecting device. 
     In a similar manner, other power supplies or converters can be added to the displayed power system topology. For example,  FIG. 5  illustrates the Topology display after adding further converters labelled PC 1  and PC 2 , the converter PC 1  having been added by selecting the input voltage line to highlight it, selecting the desired converter in the database window  33 , and selecting the button  36  to add this converter to the input voltage line, and the converter PC 2  having been added by selecting the converter PC 1  or its output voltage rail V 1  to highlight these, selecting the desired converter in the database window  33 , and selecting the button  36  to add this converter to the output voltage rail V 1 . Because the converter PC 1  and its output rail V 1  are highlighted in the panel  30  as shown in  FIG. 5 , the lower panel  32  displays information for this converter and rail, and the caption  37  in the upper panel reads “Power converters to add to Rail V 1 ”. 
     As shown in  FIG. 5 , the power converter PC 1  is an isolating SMPS or brick which is represented in a similar manner to the power converter PC 0 , and the power converter PC 2  is a VRM which is identified by an icon showing a rectangular waveform (representing that this is a switch mode power supply without isolation) and the label VRM, as well as by its colour as described above. 
     In a similar manner, further power converters PC 3  and PC 4  are added to the output voltage rail V 1  of the converter PC 1 , and a further power converter PC 5  is added to the input voltage rail, to produce the Topology display as shown in  FIG. 6 . The converter PC 3  is a VRM which is represented in a similar manner to the converter PC 2 , and the converter PC 5  is a brick which is represented in a similar manner to the converters PC 0  and PC 1 . The converter PC 4  is a liner regulator or LDO, for which the icon shows a ramp representing a linear function, and the label LDO, as well as being identified by its colour as described above. In each case, the output voltage and current characteristics are displayed in the panel  30  adjacent the respective converter. It will be appreciated that the topology of the power system as shown in  FIG. 6  is the same as that shown in  FIG. 1 . 
     With the addition of each power supply or converter to the power system topology as described above, the computer also derives from the database preferred or default values of the configuration information for the respective converter, so that this information can be subsequently (possibly after modification by a sophisticated designer) downloaded to configure the power supply controller  17  in a manner to ensure proper operation. At the same time, the computer operates through the graphical interface to preclude errors in the power system topology. For example, the computer can prevent any non-isolating converter from being attached to the input voltage line, and can ensure that each converter can only be added to a rail or line having a voltage suitable as an input voltage for the converter, and so on. 
     Having determined the topology of a power system in the manner described above, a power system designer can also specify a power-up sequence for the converters of the power system, for which the Sequence tab is selected to display a Sequence display which, as shown in each of  FIGS. 7 to 11 , comprises a graphical panel  40  and an upper panel  41  above the panel  40 . For the power system topology of  FIG. 6 , on initial selection of the Sequence tab the Sequence display is as shown in  FIG. 7 , in which the display in the graphical panel  40  is the same (except for any highlighting, which is removed) as the display in the graphical panel  30  of the Topology display as shown in  FIG. 6 . Thus the Sequence display graphical panel  40  also shows the power system topology. 
     The upper panel  41  of the Sequence display represents a startup (i.e. power-up) sequence for the power supplies or converters of the power system in the form of a square matrix or grid of selection or check boxes. Each row of the grid corresponds to a respective one of the power converters PC 0  to PC 5  in the power system, and each column of the grid corresponds to a respective one of the rails V 0  to V 5  on which the power converters produce their respective output voltages. A startup or power-up sequence is represented in the panel  41  by check-marks or ticks in respective boxes of the grid as further described below. 
     For example, if it were desired to power up the converter PC 1  only after the converter PC 0  has been enabled and is producing on its output voltage rail V 0  a voltage which exceeds the threshold voltage VT 0  as described above with reference to  FIG. 2 , then the check box in the second row, labelled “Startup PC 1  after:” and the first column, labelled “Rail V 0 ”, would be selected to place a check-mark or tick in this box. Thus this grid in the panel  41  provides a verbal representation of the power-up sequence, in this case in the form “Startup [the power converter] PC 1  after [the] Rail V 0  [is active, i.e. has a voltage produced by the power converter PC 0  that exceeds the respective threshold voltage VT 0 ]”. This verbal message is enhanced by a corresponding change in the graphical display as described later below. 
     Referring to  FIG. 7 , it can be seen that without any specific sequencing information being provided, some of the boxes of the grid are shown hatched to indicate that they can not be selected, and some of these hatched boxes also contain ticks, these indications being provided automatically by the computer. More particularly, it can be seen that all of the boxes of one diagonal of the square grid are hatched and can not be selected, because it is not possible for any of the power converters to be powered up after its own output voltage rail is active. Thus, for example, the box in the first row and first column can not be selected, because it is not possible for the rail V 0  to be active without the converter PC 0  already having been powered up. 
     Further, the hatched check boxes containing ticks are determined by the topology of the power system. As illustrated in  FIGS. 6 and 7  and as described above, in this topology each of the converters PC 2  to PC 4  receives as its input voltage the output voltage of the converter PC 1  on the rail V 1 . Thus the topology is such that each of these converters can only be powered up after the converter PC 1  is powered up to produce this voltage on the rail V 1 . This is represented in  FIG. 7  by the hatched and ticked check boxes of the grid, which are all in the column for the rail V 1 , in the rows for the converters PC 2  to PC 4 . Accordingly, the power-up sequencing inherent in the determined power system topology is incorporated into the grid in the panel  41 . This inherent sequencing is also represented in the graphical panel  40 , in that the converters PC 2  to PC 4  are displayed horizontally to the right of the converters PC 0 , PC 1 , and PC 5 . 
     Conversely, it can be appreciated that the converter PC 1  must be started before the converters PC 2  to PC 4  produce their output voltages on the rails V 2  to V 4 . Accordingly, the check boxes in the row for the converter PC 1  and the columns for these rails V 2  to V 4  are hatched and can not be selected. 
       FIG. 8  represents additional sequencing information to start up the converter PC 5  after the rail V 4  is active. To this end, a designer selects the box for the last row labelled “Startup PC 5  after:” and the column labelled “Rail V 4 ”. The computer places a tick in this selected box, and conversely determines that the converter PC 4  can not now be started after the rail V 5  is active, so that it shows the corresponding box in the PC 4  row and the V 5  column as hatched and not selectable. Further, the computer determines from the power system topology that the converter PC 1  can not now be started after the rail V 5  is active, so that it also shows the corresponding box in the PC 1  row and the V 5  column as hatched and not selectable. The display in the other boxes of the grid in  FIG. 8  is the same as in  FIG. 7 . 
     In addition, as shown in  FIG. 8  the computer provides a graphical representation of this additional sequencing information in the graphical panel  40 , by moving the icon for the converter PC 5  horizontally to the right of the converter PC 4  having the output voltage rail V 4 , and displaying an arrow  50  from the rail V 4  to the icon for the converter PC 5 . For example, the arrow  50  has a colour contrasting with the other colours of the graphical panel, so that it is prominent in the display. 
     Similarly,  FIG. 9  represents additional sequencing information to start up the converter PC 1  after the rail V 0  is active. To this end, the designer selects in the grid of the panel the box in the PC 1  row and the V 0  column. The computer places a tick in this selected box, and conversely determines that now the converter PC 0  can not now be started after any voltage rail is active, so that it shows all of the boxes in the PC 0  row as hatched and not selectable. As also shown in  FIG. 9 , the computer represents this additional sequencing information in the graphical panel  40  by moving the icon for the converter PC 1  horizontally to the right of the converter PC 0  having the output voltage rail V 0 , and displaying an arrow  51  from the rail V 0  to the icon for the converter PC 1 . Consequently, the computer also moves the display of the icons for the converters PC 2  to PC 5 , the input connections of the converters PC 2  to PC 4 , and the arrow  50  horizontally to the right to maintain the relative positions of these elements of the graphical display. 
       FIG. 10  similarly represents further sequencing information added to the Sequence display, to power up the converter PC 3  after the rail V 5  is active, and to power up the converter PC 2  after the rail V 3  is active. This further sequencing information is added by the designer selecting the respective boxes of the grid in the panel  41  as described above, with the computer entering the respective ticks in the selected boxes, hatching other boxes which consequently can no longer be selected, and horizontally shifting elements of the graphical panel (in this case only the icons for the converters PC 3  and PC 2 ) and adding corresponding sequencing arrows  52  and  53 , as shown in  FIG. 10 . 
     Although as described above the sequencing information is added by selecting check boxes in the grid displayed in the upper panel  41 , it can be appreciated that such information can alternatively be provided in any other desired manner, for example by selecting and dragging icons in the graphical panel  40 . Changes to the sequencing information can similarly be entered by a designer in similar manners. In each case the computer maintains synchronism between the information displayed in the grid of the panel  41  and in the graphical panel  40 , and prevents any attempt to sequence the converters in a way which would result in an inoperable power system. 
     Thus it can be appreciated that, using the Topology and Sequence displays as described above, even an inexperienced person can very quickly design a desired, possibly complex, power system topology and its sequencing in an intuitive manner and without introducing errors which would detract from or prevent proper operation of a resulting power system. 
     The Sequence display as described above provides for a startup sequence for the power converters. A normal shut-down sequence is typically the reverse of the startup sequence, so that configuration information for this is easily determined by the computer, as described further below by way of example. In addition, configuration information for shut-down sequencing in a fault situation can also be determined by the computer, which accordingly can generate all of the configuration information for a fully functional power system from the design information provided as described above. As indicated above, any of this configuration information can be modified by a designer selecting, for example, the Advanced tab. 
     The power converter startup sequence illustrated in  FIG. 10  is a linear sequence, in that the converters are enabled one after another in the order PC 0 , PC, PC 4 , PC 5 , PC 3 , and PC 2 . The power system topology and the graphical interface are not limited to linear sequences, but can also accommodate diverging and converging sequences. An example of startup sequencing using both diverging and converging sequences is illustrated in  FIG. 11 . It will be appreciated that as shown in  FIG. 11  the topology of the power system is the same as that shown  FIG. 1  and in  FIGS. 6 to 10 , but the sequencing is different from that described above. 
     Referring to  FIG. 11 , the Sequence display is again illustrated in the same manner as in  FIGS. 7 to 10 . As shown in the graphical panel  40  by arrows  60  and  61  and a horizontal displacement of the power converters PC 1  and PC 5  to the right relative to their positions in  FIG. 6 , each of these converters PC 1  and PC 5  is enabled or started up after the output voltage rail V 0  of the converter PC 0  is active. In the grid of the upper panel  41 , this is represented by two ticks in the boxes of the V 0  column, for the rows for PC 1  and PC 5  respectively. This represents a diverging sequence, i.e. a sequence in which two or more converters are enabled in response to power-up of a preceding converter in the sequence. 
     Similarly, a diverging sequence is shown in  FIG. 11  for the rail V 5  at the output of the converter PC 5 , by arrows  62  and  63  from this rail to the converters PC 3  and PC 4  respectively. In the grid in the panel  41 , this diverging sequence is represented by two ticks in the V 5  column, for the rows for PC 3  and PC 4  respectively. 
     As also shown in  FIG. 11  by an arrow  64  from the rail V 2  to the converter PC 3 , and a relative horizontal displacement of the icon for the converter to the right, this converter PC 3  is enabled in the startup sequence only when both of the rails V 2  and V 5  are active. This represents a converging sequence, and is also represented in the grid in the panel  41  by two ticks in (unhatched, selectable) boxes of the row for startup of this converter PC 3 , in the columns for the rails V 2  and V 5  respectively. 
     From  FIGS. 10 and 11  and the above description it can be appreciated that not only does the graphical panel  40  provide a clear graphical illustration of the startup sequence, but this is also represented fully in the grid of the panel  41 , in the unhatched, selectable boxes of which a single tick in a row and column represents a linear sequence, two or more ticks in a column represent a diverging sequence, and two or more ticks in a row represent a converging sequence. 
     It can be appreciated that, as the graphical Sequence display in each of  FIGS. 7 to 11  also illustrates the topology of the power system as developed using the graphical Topology display of  FIGS. 3 to 6 , it is alternatively possible to merge the functions of the Topology display into those of the Sequence display and to use the resulting combined display instead of these two separate displays. Such a combined display can include the graphical panel  40  (and hence also the graphical panel  30 ), as well as one or more other panels containing for example the information of the panels  31 ,  32 , and  41  as described above. The functions of defining the topology and sequencing of the power converters in a power system can combined and/or partitioned in these and various other different ways in accordance with different embodiments of the invention. 
       FIG. 12  illustrates a block diagram of a general purpose computer  70 , and a power supply controller  17  for controlling and monitoring output voltages of controlled power supplies or converters as described above. The computer  70  includes a processor  71  and associated memory  72  and, coupled to the processor  71 , a display device  73  which provides the displays as described above, one or more input devices  74  as also described above, a store  75  for storing information including the database referred to above, and an interface  76  via which information can be exchanged between the computer  70  and the controller  17 . 
     In addition,  FIG. 12  shows the NVRAM  77  and control unit(s)  78  of the controller  17 , the control unit(s)  78  including the state machines (six converter state machines and one input state machine) referred to above. Information is exchanged between the computer interface and the NVRAM  17  via a path which is shown dashed in  FIG. 12  to indicate that this need not be present except during such information exchange. Because the NVRAM  77  provides non-volatile storage, configuration information stored in it is retained in the absence of any power supply to the controller  17 , for example when a circuit card on which the controller  17  and the controlled power supplies are provided is removed from equipment so that the input voltage is absent. On power-up of the controller  17 , the stored configuration information from the NVRAM  77  is copied into shadow registers of the control unit(s)  78  for operation of the controller  17 , as described in the related applications. 
     Conveniently, the configuration information is mapped in the NVRAM  77  in a manner which matches a mapping of the shadow registers in the control unit(s)  78 , so that this copying of configuration information can be carried out easily and quickly. Similarly, the computer  70  can conveniently map this configuration information in a similar manner in its memory  72  (and/or in the store  75 ), during the steps of defining the topology of the power system and the sequencing of the controlled power supplies as described above, so that it can easily be transferred to the NVRAM  77 . As indicated above, during a power system design process the power supply controller  17  and the controlled power supplies or converters can be provided on an evaluation board, and this transfer of configuration information from the memory of the computer  70  to the NVRAM  77  of the controller  17  can be initiated from the computer after selection of the Evaluation Board tab of the display. 
     As described above, most of the configuration information comprises voltages and time periods associated with each of the controlled power supplies or converters. It can be appreciated that, on the addition of each converter to the power system topology as described above, it is a simple matter for the computer  70  to read this information from the database in the store  75  and to place it in the appropriate positions in the memory  72  (and/or the store  75 ) for subsequent transfer to the controller  17 . For example, each voltage or time period of the configuration information can be mapped to a respective 8-bit byte in the memory  72 . 
     For sequencing the controlled power supplies or converters as described above, the configuration information includes further bytes examples of which are illustrated in  FIG. 13 . More particularly, these bytes comprise one byte for each of the controlled power supplies for each of the startup, normal shutdown, and fault shutdown sequences.  FIG. 13  illustrates the startup bytes STRTEN(n), where n=0 to 5 identifies the respective converters PC 0  to PC 5 , for the startup sequence shown in  FIG. 10 , and the normal shutdown bytes SHDNEN(n) for the reverse sequence; fault shutdown sequence bytes are not shown in  FIG. 13  but are similarly provided.  FIG. 13  also shows a byte CONFIG which identifies the presence of the converters PC 0  to PC 5 . 
     In each of the bytes shown in  FIG. 13 , a logic 1 in bit positions  0  to  5  identifies the converter state machine (CSM) for a respective one of the converters PC 0  to PC 5 , and bit  7  is always a logic 0. Bit  6  in the byte CONFIG is also 0, and in the other bytes bit position  6  identifies the input state machine (ISM). 
     It can be seen that the startup sequence PC 0 , PC 1 , PC 4 , PC 5 , PC 3 , PC 2  illustrated by way of example in  FIG. 10  is represented in the STRTEN(n) bytes of  FIG. 13  by a logic 1 in bit  6  of STRTEN( 0 ) indicating that the converter PC 0  is enabled in response to the input voltage monitored by the ISM, in bit  0  of STRTEN( 1 ) identifying that the converter PC 1  is enabled in response to the output voltage V 0  of the converter PC 0 , and similarly in bit  1  of STRTEN( 4 ), bit  4  of STRTEN( 5 ), bit  5  of STRTEN( 3 ), and bit  3  of STRTEN( 2 ). For a converging sequence, the corresponding STRTEN(n) byte would have more than one logic 1 bit for which an AND function is implied. For example, for the converter PC 3  in the sequence illustrated in  FIG. 11 , each of bits  2  and  5  of the byte STRTEN( 3 ) would be a logic 1. 
     Conversely, the reverse sequence for normal shutdown, i.e. the shutdown sequence PC 2 , PC 3 , PC 5 , PC 4 , PC 1 , PC 0  for the startup sequence illustrated in  FIG. 10 , is represented in the SHDNEN(n) bytes of  FIG. 13  by a logic 1 in bit  6  of STRTEN( 2 ) indicating that the converter PC 2  is disabled in response to the input voltage monitored by the ISM falling below a shutdown voltage threshold, in bit  2  of SHDNEN( 3 ) identifying that the converter PC 3  is disabled in response to the output voltage V 2  of the converter PC 2  falling below a shutdown threshold, and similarly in bit  3  of SHDNEN( 5 ), bit  5  of SHDNEN( 4 ), bit  4  of SHDNEN( 1 ), and bit  1  of SHDNEN( 0 ). For a diverging startup sequence, and hence a converging shutdown sequence, the corresponding SHDNEN(n) byte would have more than one logic 1 bit for which an AND function is implied. For example, for the converter PC 5  in the startup sequence illustrated in  FIG. 11 , each of bits  3  and  4  of the byte SHDNEN( 5 ) would be a logic 1. 
     Also as illustrated in  FIG. 13 , a logic 1 in each of bits  0  to  5  of the byte CONFIG represents that each of the converters PC 0  to PC 5  is present in the power system topology; the absence of any of the converters from the power system is represented by a logic 0 in the corresponding bit of this byte. Further bytes can be provided for similarly identifying the presence of one or more of the converters on respective daughter boards, as described in the related application Ser. No. 10/428,136. 
     From the above description of the manner in which the bytes illustrated in  FIG. 13  correspond to the power system topology and sequencing as also described above, it can be appreciated that the computer  70  can easily set up these bytes in their mapped locations in the memory  72  as the power system topology and converter sequencing are determined by the designer, with these bytes also being transferred to the NVRAM  77  and subsequently to the shadow registers in the control unit(s)  78  of the controller  17  as described above. 
     Although details of a specific embodiment of the invention are described above, these are given only by way of example and numerous changes can be made. In addition to the possible changes mentioned above, some of these changes include the following. 
     Although in  FIGS. 7 to 11  the sequencing of the power supplies or converters is represented graphically by both the horizontal positioning of the converters and arrows such as the arrows  51  to  53  and  60  to  64 , either the horizontal positioning or the arrows may instead be used alone, and each of these can be replaced by any other desired way of representing the sequencing. For example, the sequencing may be represented by vertical instead of horizontal positioning, and/or by numbering the converters in the determined sequence instead of, or in addition to, illustrating the sequence by arrows. Illustrating the sequencing may, if desired, involve a rearrangement of the illustration of the topology of the power system. 
     As indicated above, other ways, such as drag-and-drop editing, may be used instead or as well as those described above for providing topology and/or sequencing information to the computer, and this may result in modifications of the respective displays. For example, sequencing information may be provided by selecting displayed icons in turn in a desired sequence, and/or by dragging icons in accordance with desired sequence positions. In such cases the grid  41  in the Sequence display may be dispensed with or provided in a separate display, and if displayed is maintained in synchronism with the illustration in the graphical panel by the computer as discussed above. 
     By way of further example, in the Topology display, instead of first selecting power supplies or converters from the database, icons representing the power converters can be dragged and dropped in their desired positions on the respective voltage lines. In response to the placement of each such icon, the computer can open a window on the display to request information on desired characteristics of the respective power converter, and can then perform a look-up in the database to locate power converters in accordance with these characteristics for selection by the designer. Accordingly, the upper panel  31  of the Topology display can be omitted or provided elsewhere, and similarly the lower panel  32  can be omitted from this display. As already noted, the functions of the Topology and Sequence displays can be combined in a single display. 
     In addition, although the embodiment of the invention described above relates to a particular type of power supply controller and to particular types of controlled power supplies or converters, these are given only by way of example and the invention is also applicable to other types of controller and controlled devices. For example, instead of there being a single power supply controller  17  as described above, the functions of this may be distributed among two or more control devices, for controlling larger numbers of power converters and/or for convenience, and one or more such controllers can be incorporated into the controlled power supply units themselves. 
     Instead of using a general purpose computer  70  as described above, it can be appreciated that displays such as those described above can alternatively be provided by dedicated hardware providing similar or equivalent functions. It will also be appreciated that the invention also extends to the computer or other hardware programmed or controlled to operate in a manner to provide the displays as described above, to the software or firmware for providing such programming or control, and to a computer-readable medium storing instructions which, when executed, provide such programming or control. 
     Thus although particular embodiments of the invention and examples have been described above in detail, it can be appreciated that numerous modifications, variations, and adaptations may be made without departing from the scope of the invention as defined in the claims.