By setting .option warn=1 the Safe Operation Area check algorithm is enabled. In this case for .op, .dc and .tran analysis warning messages are issued if the branch voltages of devices (Resistors, Capacitors, Diodes, BJTs and MOSFETs) exceed limits that are specified by model parameters. All these parameters are positive with default value of infinity.

The check is executed after Newton-Raphson iteration is finished i.e. in transient analysis in each time step. The user can specify an additional .option maxwarns (default: 5) to limit the count of messages.

The output goes on default to stdout or alternatively to a file specified by command line option --soa-log=filename.