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TINA/Spice/TLV8542: Spice Model Misleading and Wrong

Michael Slitts
Prodigy 40 points
Part Number: TLV8542
Other Parts Discussed in Thread: TINA-TI, , LMP8672, LPV802, LPV542, LMH6724, TLV8544

Tool/software: TINA-TI or Spice Models

Hello Precision Amplifiers Forum,

This may belong in the Simulations and Models Forum, but I believe this forum will best answer my immediate question/concern.

I have been very hard pressed to find a model of the TLV8542, simply because I need it in some sort of library/component form so that I can use it in a circuit board design.  The only models offered on the TI site are a .LIB file, which is the library extension for KiCad.  When attempting to import this LIB file into KiCad there is an error that is just a Chinese character.  The only other option is the SPICE model which I wouldn't mind having because I like the ability to model things in SPICE before building them.

My second issue is with this SPICE model.   Model is a strong word, it is technically only a schematic (.TSC), but when this schematic is opened there is a basic circuit with a component labeled as TLV8542.  I assume this is where the data from the TLV8542 datasheet was generated, since there is also a graph representing Gain vs Frequency.  The problem is that in this SPICE schematic this component is NOT TLV8542, under the properties it is LMP8672.

The question: is LMP8672 even close to a valid representation for TLV8542?  I would argue that the simple fact that LMP8672 is not RRIO and TLV8542 is RRIO would massively impact all of the simulated models.

I need to use TLV8542 very specifically in an RRIO setting, and I would like to model it in SPICE using the most basic Bubba Oscillator circuit.  Are there any suggestions on components that actually exist in SPICE that would be viable representations of the TLV8542?

Best regards,

Michael Slitts

  • 0
    TI__Mastermind 49966 points

    Hello Michael,

    The TLV8542 and the LMP8672 are VERY different devices and are NOT comparable. The TLV8542 is a nanopower (500nA) op-amp designed for slow, battery powered, high impedance applications. The LMP8672 is a Low Noise, high speed, 40V precision device capable of driving 600 ohm loads at full swing while drawing several mA supply current. That is like comparing a glider to a jet plane.

    There are two simulation files available. The first is the TINA-TI "reference design" test circuit schematic (.TSC), which has the TLV8542 macro already embedded. It can only be used in TINA and it will open up directly in TINA.

    TitleCategoryTypeSize (KB)DateViews
    TLV8542 TINA-TI Reference Design TINA-TI Reference Design TSC 54 KB 07 Aug 2017 57 views
    TLV8542 TINA-TI Spice Model TINA-TI Spice Model ZIP 15 KB 07 Aug 2017 33 views

    The second is the individual TINA-TI SPICE model pacage, which contains the SPICE subcircuit (.LIB), the TINA-TI macro symbol (.TSM), and the library file (.TLD). These files are used to add the TLV8542 to the TINA library by placing them in the TINA \SPICELIB\ subdirectory.

    This model is written in the TINA-TI PSPICE dialect of XSPICE. While mostly standard using SPICE elements, there may be special settings, options or values that may not be understood by other simulators. We do this because we can extend functionality and optimize the results and functions on a known platform.

    The .LIB model may work on other platforms if they also understand these functions and dialects. You must review the error log to make sure the elements and options are interpreted correctly.

    As I recall, Kicad uses the Ngspice engine (unless things have changed). Ngspice is a strict Berkley 3f5 engine, and may not like the "dialects" and the above models may not work. Be sure to review the simulation logs.

    The SPICE models only model basic typical behavior. The TLV8542 is much closer to the LPV802,  LPV8802 and LPV542 with slight differences in supply current. These devices have "standard' SPICE models (the '802's says TINA, but they are standard SPICE) and I know they work in "other" SPICE simulators.

  • 0 in reply to Paul Grohe
    Prodigy 40 points
    Hello Paul,

    Thank you for this thorough and thoughtful response. I did not realize SPICE came in so many "dialects"!

    The .TSC is what I was referring to, where the LMP8672 component is simply labeled as TLV8542 next to a graph of gain vs Frequency. I am opening this in TINA-TI, and it may be that the macro can't find TLV8542, so it defaults to LMP8672 for some reason.

    I placed the second model package into the SPICELIB directory, and then I recompiled the library on opening TINA-TI. This did not seem to do anything; I still cannot find the component in either the SPICE macros selection tool or in the "Find Component" tool.

    Upon opening the .TSC after this recompile, the component is still LMP8672. At this point, I believe you have answered my initial question about similar model-able components, but the Modeling department has some answering to do about why this component is not being found in TINA-TI after a recompile. Also, in TINA-TI when searching components under the manufacturer drop down menu, LMH6724 is listed as manufactured by "Teaxs Instruments". Should I create a new post in their forum or can this post be shared with them?

    Thanks,
    Michael Slitts
  • 0 in reply to Michael Slitts
    TI__Mastermind 49966 points

    Hello Michael,

    Place the three files in the /SPICELIB directory, and then you must re-compile the library. This is done by selecting both "Reread library" and "Recompile library" under the Tools menu.

    The trick is that you need to run TINA in administrative mode on Win7 and above in order for it to create the resulting .IND files, as they are in the "protected" portion of the Windows directory.

    To do this, right click on the TINA launch icon in the start menu, and select "Run As Administrator" (with the resulting "OK" administration popup).  You only need to do this when updating the libraries.

    But it looks like they did not "lock" the TLV8542 library (does not have the "locked =" line in the .TLD file), so the TINA-TI version will not accept the library.  I will get that updated.

    In the mean time, use the TLV8544 model package instead. It is exactly the same model, just renamed (SPICE models only model one channel at a time).

    TitleCategoryTypeSize (KB)DateViews
    TLV8544 TINA-TI Reference Design (Rev. B) TINA-TI Reference Design TSC 54 KB 07 Aug 2017 122 views
    TLV8544 TINA-TI Spice Model (Rev. A) TINA-TI Spice Model ZIP 15 KB 07 Aug 2017 81 views