User`s guide

22 Di

ital Simulation

Initializin

Flip-Flops

To initialize all flip-flops and latches

Select one of the three Flip-flop Initialization choices in the

Digital Setup dialog box.

• If set to X, all flip-flops and latches produce an X

(unknown state) until explicitly set or cleared, or until a

known state is clocked in.

• If set to 0, all such devices are cleared.

• If set to 1, all such devices are preset.

Startin

the Simulation

To start the simulation

From the Analysis menu, select Simulate to initiate

PSpice A/D.

If PSpice A/D successfully completes the simulation, then (by

default) Probe automatically starts.

Refer to the online MicroSim

PSpice A/D Reference Manual

for more information about flip-

flops and latches.

Note that the X initialization is the

safest

settin

, since many

devices do not power up to a

known state. However, the 0 and

1 settin

s are useful in situations

where the initial state of the flip-

flop is unimportant to the function

of the circuit, such as a to

flip-flop in a frequency divider.