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"couldn't open library file opa694.lib" ltspice

Discussion in 'General Electronics Chat' started by istemihan, Oct 18, 2015.

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  1. istemihan

    istemihan New Member

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    hi everyone, i am a new user in ltspice. i want to work with opa694 in an easy circuit but i get an warning "couldn't open library file opa694.lib". actually, it was working two days ago. what happened and it is not working now i really don't know. please give me an idea or where is my fault?
     

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  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Check that the .lib file is in either the LTspice installation's /lib folder, or in the same folder as your .asc file.
     
  3. istemihan

    istemihan New Member

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    thank you alec_t. it is working now. it was in lib folder. when i put it in the same folder as my .asc file it works well.
     
  4. dave

    Dave New Member

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  5. SuzanneOC

    SuzanneOC New Member

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    Hi, I have just started working with LTSpice on a basic circuit. I need to use opa625 from TI but cannot see any opa type opamps in my LTspice library. I am working in LTSpice IV. Is there a way to update the library? i have tried to use the PSpice opamp model from TI but I got an error regarding different no. of pins etc. I see in your post you mention opa694 and I was wondering where did you get access to that?
     
  6. eTech

    eTech Active Member

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    Hi


    There are different opinions on how to manage access to third party components. But one way that will work is to keep the component definition files in the same folder as the schematic file. I'm sure others will have different opinions about this.

    Regarding the pins....

    If you look at this line in the opa625.txt file:
    ---------------------1---2--- 3---4-----5-----6 <-----pin order
    .SUBCKT OPA625 INP INN VCC VEE OUT MODE <-----pin names

    The pin order follows the device name. The pin names can be arbitrary but the order, left to right, is important.
    The pin order must map to the pin order in the symbol. Sometimes, with third party devices, the pin order doesn't map correctly.
    Not that this is wrong, but it may have been designed for use with a another party's symbol. So you, as the user, need to check this before using the model.

    You can look at the symbol pin order:
    Place the opamp2 symbol on the schematic
    rht-clk the symbl,
    clk open symbol
    On the menu bar, clk "view" -> pin table

    This will show the pin name mapping and pin number. Again, the name is arbitrary, but the pin number is what is used to map the symbol pin to the subckt pin. The significance of the symbol pin name is identifying its function for the device (but is not always the case, sometimes just numbers are used).

    Now...to answer your pin question. If the number of pins used in the symbol does not match the number of pins in the subckt definition, the symbol will produce an error regarding a pin mismatch. One thing I have found is that LTspice also complains if numbers have been skipped in the symbol pin numbering sequence.

    Anyhow, if you look at the number of pins defined in the subckt, there are 6.
    But if you look at the number of pins defined in the opamp2 symbol, there are only 5.

    So, you will need to copy the opamp2 to your schematic folder, rename it, then edit it to add the "MODE" pin.
     
    Last edited: Apr 22, 2016
  7. SuzanneOC

    SuzanneOC New Member

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    thanks etech. The first third party model I used from the TI site was for a Pspice model. When that didnt work I downloaded the Spice model. However there is not .txt file in this folder only the following opa625.lib, opa625.tld, opa625.tsm. I used the .txt file in the PSpice model but I don't know what to do here?
     
  8. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    That is one of the TI encrypted models that works only with the TINA simulator which is nothing but a come on to buy this expensive third-party product. I detest TI for encrypting their models. I now go out of my way to avoid designing-in TI products into my consulting gigs. I bash TI about it every chance I get. The idiot at TI that come up with this should be fired...
     
  9. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    SuzanneOC, you already have your own thread for this topic here: http://www.electro-tech-online.com/...aph-of-varying-outputs-and-not-inputs.147921/. Please carry on your discussion there.

    Do not hijack someone else's thread to ask your own question. That is against the rules.

    Thread locked. If the OP wants to reopen the thread, he can send a PM to either myself or one of the other moderators to reopen.

    Matt
     
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