Problem of Convergence in simulating a model using Cadence Orcad 16.6 Pspice software?
Although this is an old question.  It would be worth noting that there are 3 things going wrong here.  Firstly, ITOL should be lowered to be 1/10 of your lowest current, as well as IREL.  This makes things take longer, but you need to have enough resolution for convergence.  The biggest change should be to set the simulator to use the "Gear" method for convergence instead of trapezoid.  What I believe that you have is something that is not converging with trapezoid due to resolution.