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LM7800: Simulation Convergence Issues when simulating alongside LM61495

Ayman Ahmad
Prodigy 90 points
Part Number: LM7800
Other Parts Discussed in Thread: LM61495

Hi,

I've been getting convergence issues when trying to simulate a circuit using LM7800 and LM61496 on PSpice. At first I thought there might be a problem with the circuit so I tried simulating the circuits provided by TI on the same schematic. The simulation is rather slow and issues convergence errors at around 33% of the simulation time. This is the PSpice project project.zip. Is there something wrong with the simulation?

Regards,

Ayman

  • 0
    TI__Mastermind 29040 points

    Hi Ayman,

    I am sending this request to the owners of the two devices in your schematic.  However, here are some thoughts you may consider:

    It is common for system designs to take a while to simulate, in any simulator.  So that is to be expected for this simulation.  The convergence issues may be improved by using Auto Converge in the PSpice settings, and changing the Speed Level to 5.

    Also keep in mind that you can remove unnecessary circuit elements, such as parallel capacitors and protection diodes with perfect voltage sources. These capacitors (or diodes) will not do anything in the simulation but they may increase the matrix which needs to be solved.  Of course, if you change the perfect voltage source to be something else, then the capacitors may make an impact at the expense of slower simulation times.

    Thanks,

    Stephen

  • 0
    TI__Mastermind 47060 points

    Hi,

    Do you have a session log or error message from the output window that I can see to understand what convergence error you are having? 

    As Stephen mentioned, the PSPICE simulation may take some time to run as it is accounting for all the nets and loops in the schematic.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    TI__Mastermind 47060 points

    Also one thing I would suggest is to run the LM61495 PSPICE separately from the LM748. 

    I would modify the LM61495 PSPICE transient model available on the product folder to the desired application condition and run the simulations separately.

    This way the simulation convergence time is significantly reduced.