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UCC28C56H: Pspice convergence error for UCC28C56H

Manoj Gunda SVSM
Prodigy 30 points
Part Number: UCC28C56H

Tool/software:

Hello ti team 

we have developed a simulation model for flyback 100kHz application. all the recommended values has been placed as per datasheet. 

but it gives convergence error.

can you help me in resolving this

below is the error from pspice. also attached the screen shot as well.

Reading and checking circuit
Circuit read in and checked, no errors
Calculating bias point for Transient Analysis
Starting GMIN stepping
Starting power supply stepping
Starting pseudo-transient algorithm
INFO(ORPSIM-16594): To improve Pseudotransient Convergence and Performance, set following options to relax stabilization criteria for capacitor currents and inductor voltages: PTRANABSTOL=1e-5, PTRANVNTOL=1e-4
WARNING(ORPSIM-16534): Using high values of ITL4 for Speed Level > 0 may increase total simulation job time.
Convergence problem in transient bias point calculation
These voltages failed to converge:
V(N00668) = 0V \ -4.021uV
V(N00675) = 0V \ -4.021uV
V(N03916) = 0V \ -2.307uV
V(N07334) = 12.73mV \ -24.30mV
V(GATE) = 8.507uV \ 7.016uV
ERROR(ORPSIM-15661): 5 of 5 errors shown. See output file for complete list
These supply currents failed to converge:
I(X_U1.EMY19) = -845.64nA \ -844.55nA
I(X_U1.XDRIVE.EB1) = 482.29nA \ 502.17nA
I(X_U1.XLATCH.X1.E1) = -1.901uA \ 0A
I(X_U1.XLATCH.X3.E1) = -571.38nA \ -1.239nA
I(X_U1.XLATCH.X4.E1) = -1.901uA \ 0A
ERROR(ORPSIM-15661): 5 of 7 errors shown. See output file for complete list
ERROR(ORPSIM-15660): These devices failed to converge
X_U1.XLATCH.X3.E1
X_U1.GBDISCH
X_M2.M1
X_U1.XDRIVE.M2
Q_Q3
ERROR(ORPSIM-15659): Discontinuing simulation due to convergence problem
INFO(ORPROBE-3185): Simulation paused

  • 0
    TI__Guru 74115 points

    Hi,

    Please provide your simulation circuit. 

  • 0 in reply to Hong Huang
    Prodigy 30 points

    flyback.zip

    Here is the pspice circuit , looking forward to here from you at the earliest.

  • 0 in reply to Manoj Gunda SVSM
    TI__Guru 74115 points

    Hi,

    Yes, the issue is due to convergency, but it looks the convergency comes from external circuit parameters not from the UCC28C56 model since the attached simulation is ok to run from our side, you can check by running this simulation file.

    The convergency usually needs to get fix through change the convergency settings by modifying the below as you know (you need try each to increase a bit at a time then re-run to find out - it is time consuming - but it is a simple trial-and-error). Another way is to check your design to try to get rid of not necessary circuit or components or change small value to be slightly bigger to avoid small time constants as these will need better resolution to get convergncy.

    Another way is to start with the attached and modify some at step to simulate to know which causing convergency.

    We do not know other tune up methods. You can also contact the PSpice vendor to get their help or advice how to resolve convergency issue in general as we do not have this team anymore so please contact the PSpice vendor to get more help.

    UCC28C56H PSPICE Check.zip

  • 0 in reply to Hong Huang
    Prodigy 30 points

    With the convergence settings available in the simulation file shared by you. convergence error is resolved, but can you help us in running the simulation faster . it is taking much larger time .

  • 0 in reply to Manoj Gunda SVSM
    TI__Guru 74115 points

    Hi,

    I do not know how to run it faster. The circuit contains many components. Usually if you want to a faster simulation, you need to find what can be skipped and what you want to focus. When you run a full converter simulation, it does not seem the running time can be fast.