IC - Initial Condition Model

Model Kind

Initial Condition

Model Sub-Kind

Set Initial Condition

SPICE Prefix

None

SPICE Netlist Template Format

.IC V(%1)=@"INITIAL VOLTAGE"

Parameters (definable at component level)

The following component-level parameters are definable for this model type and are listed on the Parameters tab of the Sim Model dialog. To access this dialog, simply double-click on the entry for the simulation model link in the Models region of the Component Properties dialog.

Notes

1. The Initial Condition device is used for setting transient initial conditions. The use of the device depends upon the setting of the Use Initial Conditions option, on the Transient/Fourier Analysis Setup page of the Analyses Setup dialog:

• When the Use Initial Conditions option is enabled, an operating point analysis is not performed. Instead, the node voltages specified by .IC devices are used to compute the capacitor, diode, BJT, JFET and MOSFET initial conditions. Since no operating point analysis is performed prior to the transient analysis, you should ensure that all appropriate DC source voltages are specified, if they are to be used to compute device initial conditions.
• When the Use Initial Conditions option is disabled, an operating point analysis is performed prior to the transient analysis and the node voltage is held at the value specified by the .IC device. During the subsequent transient analysis, this restraint is removed. This is the preferred method, since it allows the SPICE engine to compute a consistent DC solution.

2. If an Initial Condition parameter is specified for a particular device, it overrides (takes precedence over) the value defined by a .IC device.

Examples

Consider the Initial Condition device in the above image, with the following characteristics:

• The pin of the device is connected to net OUT
• Designator is IC1
• Initial Voltage = 10V

The entry in the SPICE netlist would be:

*Schematic Netlist:
.IC V(OUT)=10V