PSpice User Guide

PSpice User Guide

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PSpice A/D User Guide Convergence and "time step too small errors" October 2019 858 Product Version 17.4-2019 © 2022 All Rights Reserved. Modelling Checks This is same as in DC analysis. Modelling circuit components on page 854. PSpice A/D Options ■ Set ITL2=100 in the .OPTIONS statement. Example: .OPTIONS ITL2=100 This increases the number of DC iterations that PSpice A/D will attempt before it gives up. ■ Increase or decrease the step values, which are used in the .DC sweep. Example: .DC VCC 0 1 .1 becomes .DC VCC 0 1 .01 Discontinuities in the PSpice models can cause convergence problems. The use of larger steps may help to bypass the discontinuities, while the use of smaller steps may help PSpice A/D find the intermediate answers, which will be used to find the point, which doesn't converge. In some cases, smaller steps can improve convergence, because they help PSpice A/D find a "path" from the valid DC solution at one point to the valid solution at the next. ■ Do not use the DC sweep analysis. Example: .DC VCC 0 5 .1 VCC 1 0 becomes .TRAN .01 1 VCC 1 0 PULSE 0 5 0 1 In many cases, it is preferable to use the transient analysis to ramp the appropriate voltage and/or current sources. The transient analysis tends to be more robust, and is sometimes faster.

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