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Subsections

C: Capacitor

Syntax

Cxxxxxxx n+ n- value
Cxxxxxxx n+ n- expression
Cxxxxxxx n+ n- value {IV=initial-voltage}
.CAPacitor label n+ n- expression

Purpose

Capacitor, or general charge storage element.

Probes

The following probes are available in addition to those available for all basic elements.

DT
Time step. The internal time step used for this device for numerical integration. It is not necessarily the same as the global time step.

TIME
Time. The time of the most recent calculation of this device. It is not necessarily the same as the global time.

TIMEOLD
The time of the previous calculation of this device. It is not necessarily the same as the global time.

TIMEFuture
The latest time for the next sample, as determined by this device.

CHarge
The charge stored in this capacitor.

Q
The same as Charge.

Capacitance
The effective capacitance of this device. For a fixed capacitor, it is constant, but it will vary if it is nonlinear.

DQDT
The time derivative of charge. Hopefully this is the same as current, but it is calculated a different way and can be used as an accuracy check.

DQ
The change in charge compared to the previous sample. Its primary use is in debugging models and numerical problems.

Comments

N+ and n- are the positive and negative element nodes, respectively. Value is the capacitance in Farads.

The (optional) initial condition is the initial (time = 0) value of the capacitor voltage (in Volts). Note that the initial conditions (if any) apply only if the UIC option is specified on the transient command.


next up previous contents
Next: Trans-capacitor Up: Circuit description Previous: Summary   Contents
Al Davis 2000-09-04