ERROR -- Convergence problem in transient analysis

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.

 

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.