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TINA/Spice/OPA320: Problem using SPICE model in LTSpice

Patrick Ruf
Genius 4890 points
Part Number: OPA320
Other Parts Discussed in Thread: TINA-TI, OPA2192, , OPA192

Tool/software: TINA-TI or Spice Models

Hi,

I want to simulate the OP320 in LTSpice. I know TI does not support LTSpice but there are reasons for us to use LTSpice intead of TINA. Also simulating OPA2192 in LTSpice was successful.
It looks as if the results for DC anslysis are ok. But AC analysis results look strange. The test circuit is a Sallen-Key low pass filter. If the supply voltage is 5V (single supply) AC analysis result is correct. If supply voltage is 3.3V then AC analysis result is wrong. Doing the same simulation with OPA2192 all the AC analysis results are ok.

Attached are two print screens showing both 5V and 3.3V supply case and corresponding AC analysis results.

Any ideas what might be the problem?

Thanks and best regards,

Patrick

  • 0
    TI__Mastermind 37195 points

    Patrick,

    I tried your circuit in TINA and didn't find a discernible difference in AC response between 3.3V and 5V operation.
    The plots appear below and the TINA schematic file is attached.

    Regards,
    John

    opa320_sk.tsc

  • 0 in reply to John Miller - Sensing
    Genius 4890 points

    John,

    Thanks for testing in TINA. I did test it as well with TINA, no problems so far. Unfortunately this does not help me much.
    What I have seen is that in a short transient analysis (sine wave 1kHz, 1.5V offset, 0.5V amplitude) the OPA320 model output shows some kind of settlement in the first 0.1us from half of the supply voltage, where as the OPA2192 (OPA192) output starts right from 1.5V. Maybe this has to do with the implemented shutdown function in the OPA320 and this maybe affects the AC analysis in LTspice (?).

    Regards,
    Patrick

  • 0 in reply to Patrick Ruf
    TI__Mastermind 37195 points
    Pruf,
    Unfortunately we can't give any specific advice because your simulator's end user license agreement forbids it.
    At this point, there's not much I can say other than TINA - and many other Spice simulators - have the option starting a transient sim from zero initial conditions, or from an initial DC operating point. Experimenting with that may help.
    Regards,
    John