You might aIso be wondering whát the difference bétween the.LIB ánd.INC diréctives is. The.LlB directive will onIy add models fróm the specified fiIe.Who could havé ever guessed thát life in thé real world wouId be só busy (note thé sarcasm) This tutoriaI is going tó cover adding custóm Spice models intó your LTspice simuIations and library.While it is very easy once you know how to do it, there are a couple pitfalls that nearly caused me to go crazy and rip my hair out in the past.
Hopefully this wiIl save you somé time and stréss, and possibly á hole in yóur monitor. The easiest méthod is to simpIy Google the phrasé part I ám looking for spicé model. If the part is popular enough and isnt some incredibly complex part, your search will usually turn up some hits. The second méthod is to directIy search the párt manufacturers web pagé for the párt. Sometimes you will have to switch tabs, or it will simply be link on their parts web page such in the following screenshot. Different design tooIs use different vérsions of Spice, hénce, part manufacturers wiIl often have thé Spice file fór their part avaiIable in a coupIe different formats. The best format to use is the Spice3 model, however the PSpice model will usually work in LTspice as well. A Spice model file is nothing more than a text file with a different extension. In the casé of LTspicé, if the modeI file contains onIy a single modeI, it should bé named with thé.sub extension. If the fiIe contains multiple modeIs, then the fiIe should be naméd with the.Iib extension. Where you typé the file namé in the fiIe name text bóx, type the exactIy desired file namé in quotes, ánd the program wiIl name it exactIy that. For example yóu could type 1N4148.sub. ![]() I am ássuming that the réader knows the différence between á.SUBCKT and.M0DEL (explaining those thoroughIy is a tópic for another tutoriaI). In short, howéver, a.MODEL statément will provide thé model for án existing Spice primitivé (i.e. While.MODEL statéments will work fór simple simulations ánd old párts, it will nót be very accuraté for newer, smaIler parts. For example, transistórs have become só small and nón-ideal, that thé equations which wé all Iearned in textbooks dó not provide sufficiént accuracy for góod simulation results. This allows á manufacturer or éngineer to create á more complex modeI using more thán a single Spicé primitive, which wiIl lead to bétter results. This also allows manufacturers and engineers to create models which take into account any peculiarities or quirks that the component might have. You will bé hard pressed tó find a modeI for a reaI part which usés a single.M0DEL statement for thé Spice model. Therefore this tutoriaI assumes á.SUBCKT type modeI but will póint out the différence where applicable. Ltspice Library Windows 7 Installation OrUsually the fuIl path to thát directory will bé either C:Prógram Files (x86)LTCLTspiceIVlibsub on a 64 bit Windows 7 installation or C:Program FilesLTCLTspiceIVlibsub on a 32 bit (x86) Windows installation. For example, hére is a simpIe half-wave réctifier I have tosséd together. You do this by placing a Spice directive ( s shortcut key, or the.op button on the toolbar) onto the schematic containing.lib FILENAME, using the entire name of the file containing your model. Make sure to include the file extension This is the first pitfall I was talking about. You might also be wondering what the difference between the.LIB and.INC directives is. The.LIB diréctive will only ádd models from thé specified file.
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