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LTspice, Warning node is floating

Discussion in 'General Electronics Discussion' started by Vinasse, Oct 15, 2015.

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  1. Vinasse

    Vinasse

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    Oct 14, 2015
    Hello,

    As my first question was answered so quickly, I can't resist to put another one.

    Still trying to simulate a Flyback converter with a Viper16L from ST, when I'm running the simulation multiple warning appear in the log file, "Warning node Viper16L (D100) is floating" except that all the "pins" of the Viper16L are connected. I don't understand, maybe it is something inside of the component ?

    It would be really nice if someone could help me on this.

    Have a nice day !

    [Harald Kapp]Atttachments deleted upon request by op.
     
    Last edited by a moderator: Nov 19, 2015
  2. eetech00

    eetech00

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    8
    Nov 17, 2014
    Post an image of the schematic and the schematic.asc file
     
  3. Vinasse

    Vinasse

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    Oct 14, 2015
    Here a capture of the schematic.

    [Harald Kapp]Atttachments deleted upon request by op.
     
    Last edited by a moderator: Nov 19, 2015
  4. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    I cannot read the schematic properly but it looks as if there are two capacitors in series, bottom left. There is no DC connection to the junction, use a 100M resistor across one of them.
     
  5. Martaine2005

    Martaine2005

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    May 12, 2015
    @duke37
    If you left click on the image and then Right click, then choose View image, it will display larger. Then Right click again and it's even bigger..
    I only found that out the other day.

    Martin
     
  6. duke37

    duke37

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    Jan 9, 2011
    I found that I had to tick to put into original location before I could bodge it.
    I was wrong there are no capacitors there.

    There is however a floating wire connected to V108A and labeled 3.3V
     
    Martaine2005 likes this.
  7. Martaine2005

    Martaine2005

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    May 12, 2015
    Blimey, eyes like a hawk now!!!
    Well spotted.
    Is the 12v , middle right hand side floating too?

    EDIT: I just tried that with only text labels and didn't get an error.
    Martin
     
    Last edited: Oct 15, 2015
  8. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    Hi Trevor
    That's just a power net label I think, how is it floating?
    Adam
     
    Martaine2005 likes this.
  9. Martaine2005

    Martaine2005

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    May 12, 2015
    Just found that out Adam...

    Martin
     
  10. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Can you post the .asc file and library files for the non standard parts and I'll have a look. You can zip them up and add them as a file.
    Adam
     
  11. eetech00

    eetech00

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    Nov 17, 2014
    One problem is the Mosfet model. CTL+RHT-CLK on symbol, then change the "prefix" attribute to "X", without quotes. Save schematic, close, re-open.

    There is an additional problem with the VIPER model.
    Zip up the model files (.mod and .asy for each) and the LTspice .asc file so we can troubleshoot for you.
     
    Last edited: Oct 15, 2015
  12. Vinasse

    Vinasse

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    Oct 14, 2015
    First I would like to say thank you to all of you, I never thought that so many people would want to help me and so quickly.

    So now to answer to all of your questions.
    Eetech00 : The value of the attribute prefixe for the MOSFET is already X. And yes I think the main problem comes from the Viper model.
    Martaine2005, Arouse1973 and Duke37 : The two power labels are connected to each other right ? 3.3V with 3.3V and 12V with 12V, maybe I did something wrong.

    Anyway here is the .asc and all the models I used for the diodes, the MOSFET and the Viper16L. For the diodes I added them to the standard.dio in the LTspiceIV\lib\cmp maybe I did something wrong.

    Thanks a lot again to all.

    [Harald Kapp] attachment deleted upon request by op.
     
    Last edited by a moderator: Nov 19, 2015
  13. Martaine2005

    Martaine2005

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    951
    May 12, 2015
    You did nothing wrong, they are the text net labels. I tried it out and it does indeed work correctly.
    I am only just getting into LTspice, I normally get the 'error' by forgetting to label it! So I just connect them all.

    Martin
     
  14. Arouse1973

    Arouse1973 Adam

    5,165
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    Dec 18, 2013
    Just woke up, got a few things to do. I will have a look later, if @Harald Kapp doesnt beat me to it :)
    Adam
     
  15. Harald Kapp

    Harald Kapp Moderator Moderator

    11,522
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    Nov 17, 2011
    Don't worry, Adam, not today - too busy.;)
    I triedd hortly to simulate the circuit, but I'd have to include the unknown components into the lib or add a new lib.

    @Vinasse : have you had a look into the ressources section? There I posted a ressource on LTSPICE error messages and some tips how to remedy them.
     
  16. Vinasse

    Vinasse

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    Oct 14, 2015
    Hello Harald,

    So I checked your post, and I don't think I have any of these errors.

    I do have 3 GND but I don't think it is an error, they need to be connected.
     
    Last edited: Oct 16, 2015
  17. Vinasse

    Vinasse

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    Oct 14, 2015
    One more question, do I need to put all the attribute prefix to X for all the diode models that I added ?
     
  18. eetech00

    eetech00

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    Nov 17, 2014
    Any diode symbol that is a defined by a .subckt should have its prefix changed to X.

    BTW
    Diode V104 does not have a value specified...
     
    Last edited: Oct 16, 2015
  19. eetech00

    eetech00

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    Nov 17, 2014
    The VIPER16 model is encrypted. You will have to talk to the model supplier to work out why its not working, unless they will provide you an unencrypted model file. Then we might be able to help.

    eT
     
  20. Vinasse

    Vinasse

    11
    0
    Oct 14, 2015
    Ok thanks for the prefix, I will change them, and yes the V104 has no value, I am still waiting for a model from ST Micro. I can't find it on the web (STTH108).
     
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