boylistad

508 ⏐⏐⏐ INDUCTORS
FIG. 12.60
The transient response of v L and i R for the network of Fig. 12.59.
the bottom of the dialog box, and select New Column to obtain the
Add New Column dialog box. Under Name, enter IC (an abbreviation
for “initial condition”—not “capacitive current”) followed by the initial
condition of 4 mA under Value; then click OK. The Property Editor
dialog box will appear again, but now the initial condition appears as a
New Column in the horizontal listing dedicated to the inductive element.
Now select Display to obtain the Display Properties dialog box,
and under Display Format choose Name and Value so that both IC
and 4mA will appear. Click OK, and we return to the Property Editor
dialog box. Finally, click on Apply and exit the dialog box (X). The
result is the display of Fig. 12.61 for the inductive element.
Now for the simulation. First select the New Simulation Profile key,
insert the name InitialCond(L), and follow up with Create. Then in the
Simulation Settings dialog box, select Time Domain(Transient) for
the Analysis type and General Settings for the Options. The Run to
time should be 200 ms so that we can see the full effect of the pulse
source on the transient response. The Start saving data after should
remain at 0 s, and the Maximum step size should be 200 ms/1000 �
200 ns. Click OK and then select the Run PSpice key. The result will
be a screen with an x-axis extending from 0 to 200 ms. Selecting Trace
to get to the Add Traces dialog box and then selecting I(L) followed
by OK will result in the display of Fig. 12.62. The plot for I(L) clearly
starts at the initial value of 4 mA and then decays to 1.78 mA as defined
by the left-click cursor. The right-click cursor reveals that the current
has dropped to 0.222 mA (essentially 0 A) after the pulse source
has dropped to 0 V for 100 ms. The VPulse source was placed in the
same figure through Plot-Add Plot to Window-Trace-Add Trace-
V(VPulse:�)-OK to permit a comparison between the applied voltage
and the resulting inductor current.