ERROR -- Convergence problem in transient analysis

Discussion in 'Cadence' started by TELEPAC, Jan 8, 2004.

  1. TELEPAC

    TELEPAC Guest

    Hello all OrCAD and PSpice users.

    This is about the most oft-asked question, I know, but here it goes again!!

    Subject: ERROR -- Convergence problem in transient analysis at Time =
    482.5E-06
    Time step = 447.0E-15, minimum allowable step size = 600.0E-15
    These voltages failed to converge:
    V(SQUARE-WAVE) = 6.857V \ -12.80V
    These supply currents failed to converge:
    I(X_U12.Esqr) = -685.72uA \ 1.280mA
    These devices failed to converge:
    X_U12.Esqr

    I tried upping various values in gentle stages during simulation like:-
    RELTOL upto as high as 1
    ABSTOL = 1uA
    CHGTOL = 0.0uC to 1pC
    GMIN = 0.01u
    ITL1 = <500
    ITL2 = <150
    ITL4 = <100

    But still got bad results.

    Any further suggestions or help from the manuals on this would be
    appreciated----?

    Best, ROBIN.
     
    TELEPAC, Jan 8, 2004
    #1
  2. TELEPAC

    Jimmy Blue Guest

    Look for unrealistically low model / node capacitances
    (requiring voltage to change more than minimum accuracy
    tolerance in less than minimum timestep) and unreasonable
    stimuli (square wave with zero edge time, etc.). Things
    that take zero (or negative) time do not solve well.
     
    Jimmy Blue, Jan 27, 2004
    #2
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