FBHF|::'< SW switcher design program ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
zWelcome to SW.  This is a switcher design program that allows you to design switching power supply interactively.  The ≡ menu is accessed by pressing Alt-Space.  All the other menus are accessed by pressing Alt-Z, where Z is the first letter of the menu.  For example, the "File" menu is pulled down by Alt-F.   All menus items are available when you are at the top menu level. )
Press ESC to put this help screen away. '8 ≡ (System) menu ▄    (Alt-Spacebar)
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
\The System menu appears on the far left of the menu bar and is represented by the ≡ symbol. (
When you pull down the ≡ menu, you see 	
  About
└' ≡│About ▄
  ▀▀▀▀▀▀▀▀
åWhen you choose the About command from the ≡ (System) menu, a dialog box appears, showing copyright, author and  version information. 

Press ESC to close the box. '" File  (Alt-F) ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀
╡The File menu offers choices for starting a new design, opening old files, save working files, save existing design to a new filename, exit to DOS and back and exiting the program. 
 Open   FExit FDosShell
┌ßτ	'& File│Open  (F3) ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
yThe Open command displays the Open a File dialog box. In this dialog box you select the design file you want to work on. &
The Open a File dialog box contains: ╣
 ■ an input box with a history list
 ■ a list box to browse the directory
 ■ the standard Cancel button
 ■ OK action button
 ■ an information panel that describes the
   selected file
	Ñ
═	≡
!2'& File│Save  (F2) ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
JThe Save command saves the file that's in the active Edit window to disk. H
Use Save_As(F5) to define file name before executing Save(F2) command. &
The Save a File dialog box contains: ╗
 ■ an input box with a history list
 ■ a list box to browse the directory
 ■ the standard Cancel button
 ■ Save action button
 ■ an information panel that describes the
   selected file
	╛
µ		
:K'* File│SaveAs  (F5) ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
╥The Save_As command opens up the Save File as dialog box with a file name *.SWI, where you can save the file in the active Edit window under a different name, in a different directory, or on a different drive. »
Click or choose OK when the new file name, including the drive and directory, has been entered.  The Save command will then use the file name defined in the Save_As command. &
The Save a File dialog box contains: ╗
 ■ an input box with a history list
 ■ a list box to browse the directory
 ■ the standard Cancel button
 ■ Save action button
 ■ an information panel that describes the
   selected file
	▒
┘	ⁿ
->'$ File│DOS Shell ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
With the DOS Shell command, you can leave the program temporarily to perform a DOS command or run another program.  Please keep in mind the memory available is the total space minus the SWcad program, and there is about 100K to 200K bytes left for DOS commands. 9
To return to this program, type EXIT at the DOS prompt. '& File│Exit ▄     (Alt-X)
  ▀▀▀▀▀▀▀▀▀▀
*The Exit command terminates this program. 'D Help on Open a File Dialog Box ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀▀
╧The Open a File dialog box contains an input box, a file list, a file information panel, the standard button Cancel, one other action button (Open), plus a history list that's attached to the Name inputbox. y	
▓╙

'o ┌─ Name ──────────────────────────┐
 │                                 │
 └─────────────────────────────────┘
ÿThe Name input box is where you enter the name of the file to load, or the file-name mask to use as a filter for the Files list box (for example, *.*). '╝ ┌ Files ──────────────────────────┐
 │                                 │
 │  FILENM01.SWI  │  FILENM09.SWI  │
 │  FILENM02.SWI  │  FILENM10.SWI  │
 │  FILENM03.SWI  │  FILENM11.SWI  │
 │  FILENM04.SWI  │  FILENM12.SWI  │
 │  FILENM05.SWI  │  ..            │
 │  FILENM06.SWI  │  \DIR0         │
 │  FILENM07.SWI  │  \DIR1         │
 │  FILENM08.SWI  │  \DIR2.DIR     │
 │  ▒▒▒■▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒   │
 └─────────────────────────────────┘
¼The Files list box lists the names of files in the current directory that match the file-name mask in the Name input box, plus the parent directory and all subdirectories. ╣
 ┌──────────────────────────────────────────┐
 │ C:\TP\EXAMPLES\*.SWI                     │
 │ BOOST.SWI       52  Mar 24,1991  12:00pm │
 └──────────────────────────────────────────┘
fThe File information panel shows the path name, file name, date, time, and size of the selected file. =
None of the items on this information panel are selectable. '* ┌──────────┐
 │ [ OK ]   │
 └──────────┘
dThe OK button opens or saves a new design file and invokes the SWitcher design screen in Open mode. '0 ┌────────────┐
 │ [ Cancel ] │
 └────────────┘
]
If you choose Cancel, nothing changes and no action occurs, and the dialog box is put away. M
(Esc always cancels a dialog box, even if a Cancel button does not appear.) '* ┌──────────┐
 │ [ Open ] │
 └──────────┘
æ
In the Open a File dialog box, if you choose the Open button SW opens a new design file and places the selected file in SWitcher Design screen. '/
 Schematics ▄
  ▀▀▀▀▀▀▀▀▀▀▀
⌐Switch to graphics mode and show schematics.  The *.BGI drivers have to be in the same directory as the program directory for graphics to work. (Hardcopy not available) 
 PartsList ▄
  ▀▀▀▀▀▀▀▀▀▀
Show the list of parts. 
 OptimizeDsn ▄
  ▀▀▀▀▀▀▀▀▀▀▀▀
2Fine tune input variables to optimize the design. 
 Close ▄
  ▀▀▀▀▀▀
4Close current screen menu and go back to top level. F

SwitcherCAD selects all topologies which are capable of generating the required outputs from the stated input voltage range.  A buck ( stepdown) converter for instance is only capable of generating outputs which are lower than the input.  The following chart shows the capabilities and/or limitations of various topologies. 
Buck  (stepdown) L
     Output can only be lower than input.  Switch current must be at least
4equal to output current.  One inductor is required. 
Boost  (stepup) M
     Output can only be equal to or higher than input.  Output will  remain
φjust below input if the switcher is shut off.  Output cannot be shorted without dragging down the input.  Switch currents must be at least equal to output current times output voltage divided by input voltage.  One inductor is required. 

Buck-boost (inverting) I
     Output will be the reverse polarity of the input, but may have any
╓amplitude, limited only by switch breakdown voltage.  Switch currents must be at least equal to output current multiplied by the sum of input and output voltage divided by input voltage.  One inductor is required.  

Flyback (using a transformer) M
     Output can be any amplitude or polarity, independent of input voltage.
aSwitch current may be higher or lower than output current, depending on transformer turns ratio.  
Tapped inductor buck converter L
     Output voltage can only be lower than input voltage.  Switch currents
Uare lower than output current by an amount dependent on tap ratio and input voltage. N

     In some applications there will be several possible topologies.  Those
δusing a simple inductor will usually have higher efficiency, but may require significantly higher switch currents than a transformer or tapped inductor topology.  A flyback or buck-boost circuit can generate multiple outputs, with one well regulated, and the others moderately regulated.  A buck convertor can also generate multiple outputs, but the total power of the extra outputs must normally be less than one-half of the main output  power.  The box below the topology list area shows the estimated minimum peak switch current for the selected topology.  This  can be used as a guide to select an appropriate topology, along with other considerations such as short circuit protection (boost cannot be shorted), simplicity, or personal taste. L
     Device selection is based on the capability to operate in  a specific
Ktopology and the estimated worst case peak switch currents.  This criteria may still yield several devices in many applications.  SwitcherCAD makes the final selection  by choosing the highest frequency device with the lowest switch current rating, to minimize cost.  Lower frequency devices may yield higher efficiency, as will devices with higher-than-required switch current rating.    You may override the selected device by clicking on the desired device.  The following chart lists the characteristics of each device, grouped by family and ordered by frequency and switch current. ]

 Device  Frequency  Switch   Input    Switch
                    Current  Voltage  Voltage
,
 LT1270A    60KHz     10A      35V     60V
,
 LT1270     60KHz      8A      35V     60V
,
 LT1170HV  100KHz      5A      60V     75V
,
 LT1170    100KHz      5A      40V     65V
,
 LT1171HV  100KHz    2.5A      60V     75V
,
 LT1171    100KHz    2.5A      40V     65V
,
 LT1172HV  100KHz   1.25A      60V     75V
,
 LT1172    100KHz   1.25A      40V     65V
,
 LT1070HV   40KHz      5A      60V     75V
,
 LT1070     40KHz      5A      40V     65V
,
 LT1071HV   40Khz    2.5A      60V     75V
,
 LT1071     40KHz    2.5A      40V     65V
,
 LT1072HV   40KHz   1.25A      60V     75V
,
 LT1072     40KHz   1.25A      40V     65V
,
 LT1074HV  100KHz    5.5A      60V     75V
,
 LT1074    100KHz    5.5A      40V     60V
,
 LT1076HV  100KHz      2A      60V     75V
,
 LT1076    100KHz      2A      40V     75V
'
 Next  ▄
  ▀▀▀▀▀▀
JDone with input data entry and continue with topology and part selection. 
 Close ▄
  ▀▀▀▀▀▀
4Close current screen menu and go back to top level. 

Input Voltages. I
     Proper definition of input voltage range is important because many
Cswitching regulator parameters are dependent on input voltage.  Ripple current in the output capacitor for instance is maximum for high input voltage on a buck converter, and for low input voltage on a boost convertor. SwitcherCAD calculates most parameters at low input voltage because this is where switch currents are highest, and switch current is the limiting factor for moderate to high current designs.  Several parameters in each topology may be calculated at nominal input voltage, and a few, such as peak operating voltages, are calculated at maximum input voltage.  SwitcherCAD uses strict interpretation of voltages.  Therefore, for negative input voltages use a minus sign in front of the value and enter the largest negative number in the min column.  The actual calculations and printout are done using absolute values. N
     Minimum and maximum input voltages will define topology and peak switch
│currents, so care should be exercised in using accurate numbers.  Transient low input voltage conditions on the input must be allowed for,  because the capacitors used on the input and output of a switching will normally only allow a [hold-up] time of a few switching cycles (30 to 100 microseconds). Maximum input voltage is usually limited by breakdown voltages, which must never be exceeded, even for times less than 1 microsecond. J
     The switcherCAD printout of operating conditions states which input
╟voltage is used for each parameter.  If there is any question about [worst case] conditions, that input voltage should be set to several conditions for additional printouts to guarantee that worst case conditions are covered.  For instance, ripple current in the input capacitor of a buck convertor will maximize at an input voltage of approximately twice output voltage, and average diode current will maximize at the highest input voltage.  Thought should be given to which input voltages affect thermal conditions.   A short transient will probably have to be considered if peak switch current or breakdown voltage is exceeded, but for times less than 30 seconds, it may be ignored for thermal calculations. 
Output Currents L
     Most switching regulator designs in switcherCAD will operate from the
▀maximum load current down to zero.  They will all shift to [discontinuous] mode operation at some low value of load current, but in general this is not a problem.  SwitcherCAD assumes that the maximum stated load current is to be used for calculating worst case switch currents, and that the nominal output current is to be used for calculating thermal conditions and efficiency.  If maximum load currents will exist for longer than 30 seconds the nominal current should be set equal to maximum load current. Minimum load current is not used in any of the calculations, but may be compared in the printout with the current where the switcher shifts from continuous to discontinuous mode to see if indeed discontinuous mode is entered. '?
 OptimizeDsn ▄
 ▀▀▀▀▀▀▀▀▀▀▀▀▀
  Help file for optimize design
'█
User will be prompted to specify the Design-Screen first, and then all allowed topologies and parts will be chosen automatically on Selection-Screen.  Schematics and parts list are also available for each topology. User can further optimize the design by fine tuning each input variables.  Once in SWdesign menus, all top level commands are not accessable anymore, only F1(Help key) is still available for all levels.  Hit ESC key to quit SWdesign and go back to top level. '
åΩ'
  Print ▄
   ▀▀▀▀▀▀
+Print design data to printer or text file. 
  Watch  ▄
   ▀▀▀▀▀▀▀
≈Highlight the line of interest and click the button or press the W key to put it into watch window for monitoring use. The new line is inserted from the top of the window and will push out the bottom line if three lines have been selected before. '
  Yes ▄
   ▀▀▀▀
2Go back to previous screen and correct the error. 
  No ▄
   ▀▀▀
pContinue with the erroneous input for topology and part selection. Warning: Results might not be meaningful !!! '>
Print input, output lines and parts list to printer or file. k
 ()Input_Eqs  : All input variables.
 ()Output_Eqs : All output variables.
 ()PartsList  : List of parts.
$
Click OK to print, CANCEL to quit. ';
Define sorting criteria for capacitor database selection. a [Set Limits]
 ()Yes  use the entered data as sorting criteria.
 ()No   Ignore sorting criteria.
'2
Select inductor, capacitor or resistor database. '
 EnableAll ▄
  ▀▀▀▀▀▀▀▀▀▀
ÆIgnore input data and make all topologies and parts available for selection. Warning: Expect to see garbage outputs and divide by zero errors !!! '·╓ƒ¡V╫
IÑ╪
δ─^Ga&!3i3\5╝6É7l89O9                    