How to link a model to an OrCAD PSpice schematic?

Discussion in 'Electronics Resources' started by kender, Apr 23, 2007.

  1. kender

    Thread Starter Senior Member

    Jan 17, 2007
    263
    0
    RE: How to link a Spice model to an OrCAD schematic for further simulation?

    Colleagues,

    I’m using OrCAD PSpice for the 1st time today (although I’ve been using OrCAD for capture and layout for a long time). In the past I’ve been using LTSpice, but I want to switch to Spice with more features, such as PSpice.

    I want to simulate a switch-mode power supply (buck converter). In this buck converter I want to use a P-channel MOSFET IRF4905. There is a schematic symbol for IRL4905 in DK_TRANSISTOR.olb, when I use it PSpice gives an error “No PSpice template for Q3, ignoring”.
    The manufacturer of a IRF4905 provides some kind of Spice library (?) for it here http://www.irf.com/product-info/models/SPICE/irf4905.spi

    How can I connect the OrCAD symbol and the Spice library together ?

    I apologize in advance for this newbie question. Unfortunately, I was able to find only one OrCAD PSpice tutorial online here http://www.ee.siue.edu/~gengel/pdf/PSPICEtutorial.pdf. It’s good, but it’s very-very basic.
     
    Last edited: Jun 25, 2008
  2. gootee

    Senior Member

    Apr 24, 2007
    447
    50
    I'm just curious. What features does Pspice have that LTSpice doesn't have? Or, what extra features of Pspice made you want to switch to it?

    - Tom
     
  3. kender

    Thread Starter Senior Member

    Jan 17, 2007
    263
    0
    I don’t simulate a lot, so I’m not familiar enough with features of LTSpice and PSpice to be able to compare them. But here are the reasons, why I’ll stick to PSpice:

    1. OrCAD is my primary schematic capture tool. I just wanted to try out PSpice, and it didn’t disappoint.
    2. I, personally, found PSpice more user friendly. It took me more time to get the interpretable results from LTSpice than from PSpice.
    3. PSpice is friendlier to larger schematics.
    4. PSpice has more libraries, although there are not a lot of libraries for Linear Technology parts. I wish there were a way to import the models from LTSpice to PSpice.
     
  4. gootee

    Senior Member

    Apr 24, 2007
    447
    50
    LTSpice and PSpice models are fully compatible, since LTSpice was designed to use PSpice models. However, many of the Linear Technology products' models, WHEN they are supplied in an LTSpice installation file, are in a form that makes them simulate much faster with LTSpice but is not compatible with any other Spice. For those particular LT products' spice models, I was under the impression that the LT website has _standard_ PSpice models for them, that can be downloaded, en masse (and separately from LTSpice). To find out easily, you could ask in the LT-Spice forum, at yahoogroups.com, or, just look on the website, at linear.com

    - Tom Gootee

    http://www.fullnet.com/~tomg/index.html

    -
    .
     
  5. kender

    Thread Starter Senior Member

    Jan 17, 2007
    263
    0
    Thanks! This is a useful piece of information.

    I've checked the LT web site and Google for PSpice models of some of my favorite parts (LTC3531, LT1074, LT1025), and I couldn't find them. So far, I saw PSpice models only for LT OpAmps.
     
  6. gootee

    Senior Member

    Apr 24, 2007
    447
    50
    The models that I downloaded were not in separate files for each device. They were all in one big zip file, which probably wouldn't be found by a search for a particular part name. I found it from their page where they list all of their downloadable software (including LTSpice), and followed some link for models. I'm writing this offline, since my ISP appears to have just gone down. I'll try to get a direct link for you, after I can get to their site.

    I have the unzipped 763KB LTC.LIB file open, right now. It appears I downloaded a file named LTC.ZIP. I can't see the LT1270A switching regulator that I like. But I see more than just opamps, although, there ARE a LOT of opamps. And it looks like it might be mostly opamps. But, just looking over it quickly, I do see a video fader or two, and some instrumentation amps, an OTA, and what look like linear voltage regulators.

    It looks like there are probably at least 300 or 400 models, in the file.

    You might have better luck finding it if you go to the linear.com site and either follow their links to LTSPice or software downloads, or, use their search box to search for something more generic, such as "models", or "models download".

    OK. I'm back on line. Go to http://www.linear.com, then click on "Design Support", at the top of the page. Then click on the "Design Simulation Page" link, near the upper left corner of the page. Then click on "Spice Models", near the lower-left corner of the page. Oops. My ISP just went down again. But, unforunately, the description, there, mentions only that the file contains "the complete library of LTC op amp SPICE models for general analog circuit simulations. These models are designed for compatibility with LTSpice (SwitcherCAD), PSPICE, and PSPICE-compatible simulation programs..." etc. So , even though it does appear, from my copy, that there are at least some models for devices other than opamps in the file, it apparently does not contain many or most of the other LTC devices. That's unfortunate. Sorry.

    - Tom Gootee

    http://www.fullnet.com/~tomg/index.htm

    -
     
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