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Tina-TI IC count limitation

Nikhil Kant
Expert 1130 points
Other Parts Discussed in Thread: TINA-TI

I analysed a six opamp filter ckt  using TINA-TI for ac response. However in some standard TI examples,

downloaded as part of package, that use only two op amps ,it is stated that third opamp is not used to keep

within IC count limitations of TINA-TI. What are these limitations?

  • 0
    Guru 21975 points

    Nikhil,

    An earlier version of Tina-TI limited the number of op amps that could be simulated. The current version has no such limitation. The examples you cite were created with the previous version. You can simulate larger circuits with the new version.

    Regards, Bruce.

  • 0
    TI__Guru* 93105 points

    Hi Nikhil,

    You may find that as you increase the number of operational amplifiers in your circuit that the simulation time becomes much increased, or there may be a point where it becomes difficult for TINA-TI Spice to reach convergence. This is not a limitation specific to TINA-TI, but to PSpice simulators in general. Remember the "P" in P-Spice is for portable and differentiates it from Spice which was ran on the mainframe computers of yesteryear. Therefore, sometimes the matrices that must be solved on our "portable" computers becomes so large that a solution is not readily attained; especially if we are attempting to obtain a solution for something such as a complex transient analysis, or a circuit with multiple loops.

    The operational amplifier or other analog circuit simulation model used in your simulation has much to do with how many you can successfully place in the circuit. They vary from that of a simple ideal operational amplifier consisting of a couple of controlled sources plus passive components, to some containing hundreds of components. The more of the latter you place in your circuit, the larger the matrices associated with the circuit become. So you may find that for some operational amplifiers you can place many of them in the circuit to be simulated and can do so with ease, while other circuits may only be able to accommodate a few.

    You can usually get a feel for the model complexity when you access the model's PSpice syntax. In TINA-TI, double click on the model symbol, then click on the Enter Macro button. If the syntax listing has something like 20 or 30 lines it is a simple model that will only simulate a limited number of amplifier electrical behaviors. If it has hundreds of lines it is a more complex model that produces (simulated) electrical behaviors much more like that of the real amplifier. The latter will likely provide a more accurate representation of how the real circuit will behave, but you may find that it is more challenging for the simulator engine to resolve.

    Regards, Thomas

    PA - Linear Applications Engineering