First, make yourself a user directory under 'sym':
Before adding anything (I already did, but we will get to that).
Start LTSpice, start a new schematic and then select add component:
I get this view with my parts directory shown:
Close LTSpice for now.
For an opamp (which is what I did here), copy the OPAMP2.sym file from the sym\Opamps directory to your directory and rename it with the name you want (which is what I did in the first picture).
Now get the subcircuit file and save it in the lib\sub directory:
Now open the asy file in your user directory in a text editor:
Here is part of the file:
SYMATTR Value ADA4666
SYMATTR Prefix X
SYMATTR Description Micropower Rail to Rail amplifier
SYMATTR SpiceModel ADA4666.cir
If there are no SYMATTR lines, then add them:
Version 4
SymbolType CELL
LINE Normal -32 32 32 64
LINE Normal -32 96 32 64
LINE Normal -32 32 -32 96
LINE Normal -28 48 -20 48
LINE Normal -28 80 -20 80
LINE Normal -24 84 -24 76
LINE Normal 0 32 0 48
LINE Normal 0 96 0 80
LINE Normal 4 44 12 44
LINE Normal 8 40 8 48
LINE Normal 4 84 12 84
WINDOW 0 16 32 Left 2
WINDOW 3 16 96 Left 2
SYMATTR Value ADA4666
SYMATTR Prefix X
SYMATTR Description Micropower Rail to Rail amplifier
SYMATTR SpiceModel ADA4666.cir
PIN -32 80 NONE 0
PINATTR PinName In+
PINATTR SpiceOrder 1
PIN -32 48 NONE 0
PINATTR PinName In-
PINATTR SpiceOrder 2
PIN 0 32 NONE 0
PINATTR PinName V+
PINATTR SpiceOrder 3
PIN 0 96 NONE 0
PINATTR PinName V-
PINATTR SpiceOrder 4
PIN 32 64 NONE 0
PINATTR PinName OUT
PINATTR SpiceOrder 5
Add any SYMATTR lines immediately before the PIN and PINATTR statements.
I changed the SYMATTR values to give a correct display name (Value), the Description field for what LTSpice shows in the selector window and the SpiceModel to the model I added in the sub folder.
Here it is:
I then place it:
Right click on the part and you get this:
This can now be used in any schematic.
I went through this when I added the Wurth magnetics library a while back.
The keys are:
Put the subcircuit in the sub folder
Put the symbol file in a directory of your choosing
Make sure the SYMMATR statements point at the subcircuit properly, and edit the name and description to get an accurate representation of what it is.
Note that the subcircuit must be complete in its own right.
In your case, you are trying to create a hierarchical block; there is an excellent description at the link.
As links die, here is the procedure:
Make the schematic you desire to use as a hierarchical block and save it with a name
Now label all nets that must have external visibility and save again.
Create a new symbol. The pins on this symbol must have the same name as the labels you attached.
Save this symbol as (the names must be the same for the schematic and symbol).
If your schematic has external models or subcircuits, use the .include directive using full path names in the schematic before saving (so they do not have to be in a working directory).
You should now be able to instantiate your hierarchical block.
The first thing to do with any spice simulation problem is check your netlist, which is the easiest way to debug with graphical spice packages. If you don't have a .lib and the name of your downloaded package then you have a problem. (you can do this in view->spice netlist)
The second thing is you need to get your paths straight. If you do have a .lib statement, then the path of your .subckt file needs to follow the .lib statement. Example: if your .subckt file was named NCP1217.cir (or whatever its extension is, they are all text files anyway) was located in C:\LTC\libraries then the spice command that needs to show in the spice netlist is:
.lib c:\LTC\libraries\NCP1217.cir
If you put your file in the LTspice\lib\sub folder you don't need to provide the entire path.
There are ways through the attributes list (in your symbol files, .asy to be more specific) to include the .lib statement.
The last thing is you need your X line in the netlist to have the appropriate nodes, double check each node of the lt spice netlist and make sure it matches up with the netlist in your 3rd party model. Then if you have multiple devices, the last thing should be the name of the subcircuit.
Here is an example:
XU1 posrail negrail posterminal negterminal output DEV1376
Keep in mind that no spice model will even come close to the real world, most all models are simplified in spice to model selected parameters in the datasheet by the manufacturer and only approximate the real world. (after all if they really did a transistor model of each device, all you would have to do to create a copy of the device is download the spice file) Some models will give some kind of disclaimer as to what the model can and can't do.
Best Answer
Models and graphs are given to shown nominal , while specs are common to both and others with ;
240 mV @ 1mA.
320 mV @ 10mA.
The Min/Max ratings at given conditions should be the same.
Diodes Inc have pioneered lower voltages by improving the bulk series resistance by design and may have some advantage. (Hundreds of patents)