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TPS2491 Simulation and response to multiple short power interrupts

Paul Norris
Prodigy 70 points

Other Parts Discussed in Thread: TPS2491

Hi,

I am trying to run a transient analysis simulation of the TPS2491 in TINA but I am running into problems with TINA returning a Convergence problem. I've attached the simulation file.

Ultimately I want to be able to run a simulation whereby I subject the TPS2491 to multiple power interrupts of 50ms duration and verify what inrush current my power supply will take following the restoration of power.

Any help would be greatly appreciated.

Kind Regards,

Paul

TPS2491.TSC

  • 0
    TI__Mastermind 42795 points
    Hi Paul,
    I moved this to the simulation models forum.
  • 0 in reply to Eric Wright
    TI__Mastermind 39210 points
    Paul,

    A few questions and recommendations:

    (1) Please start from an existing TSC file id possible. We tune the simulation settings so as to avoid convergence errors while maintaining the accuracy of the sims. In this case, if you start from the following TSC file on the web, the sim on your circuit works without any convergence error.

    www.ti.com/.../slvm342

    (2) For your circuit, I noticed that the input is 0V (unit step with 0 amplitude). I would recommend using a piecewise linear input (similar to what has been released in the document above) which gives the ability to give a realistic rise time v/s a step input where the Vin jumps instantaneously.

    (3) Did you intend the GND pin to be semi-floating. I see it is connected to the GND pin but through a very large Inductance value.
  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Prodigy 70 points
    Thank you Nikhil,

    I will give (1) and (2) a try and get back to you.

    With regards to the semi floating ground, that is my intention, the 28V input supply to the unit is isolated from the main electronics using a flyback controller. The heavy filtering on the supply is intentional for EMI purposes.

    Kind Regards,

    Paul
  • 0 in reply to Paul Norris
    Prodigy 70 points
    Hi Nikhil,

    I've tried (1) and (2) and can get the simulation to work. However, the convergence error re-occurs if either the series 22uH inductors are in the circuit or there are 2.2 Ohm resistors in the circuit on the 28V and its return which would be as per our design. I think it is something to do with where I place the ground reference for the circuit, if I place it on the TPS2491 side of the inductors and resistors then no convergence error occurs.

    Can you explain why this is occurring as I would like my simulation to be as representative of the real world as possible?

    Kind Regards,

    Paul
  • 0 in reply to Paul Norris
    TI__Mastermind 39210 points

    Hi Paul,

    I checked the model internally and the GND pin is not floating (It is hard coded to 0V), which is why you might be getting the convergence error. The model is built in a completely behavioral way, so even if we make the GND pin floating, it may not provide you any additional information in this case.

    Usually from a modeling perspective, having a floating GND is most helpful when you are trying to simulate (for example) an inverting configuration circuit from a Buck device, but in this case all your nodes are positive and referenced to 0V. What additional information you do expect to get from the model by keeping the GND node configuration as you have now?

  • 0 in reply to Nikhil Gupta (Product Folder Models)
    Prodigy 70 points

    Hi Nikhil,

    Sorry for the delay in replying. I was hoping to perform the simulation with as close to real world conditions as I could.

    Thank you for your help with this, I consider this matter closed.