User`s guide

Concepts You Need to Understand 14
-3
Concepts You Need to
Understand
States
When the circuit is in operation, digital nodes take on values or
output states shown in Table 14-1. Each digital state has a
strength component as well.
Note that states do not necessarily correspond to a specific, or
even stable, voltage. A logical 1 level means only that the
voltage is somewhere within the high range for the particular
device family. The rising and falling levels only indicate that the
voltage crosses the 0–1 threshold at some time during the R or F
interval, not that the voltage change follows a particular slope.
Table 14-1
Digital States
Stat
e
Meanin
g
0 Low, false, no, off
1 High, true, yes, on
R Rising (changes from 0 to 1 sometime during the R
interval)
F Falling (changes from 1 to 0 sometime during the F
interval)
X Unknown: may be high, low, intermediate, or unstable
Z High impedance: may be high, low, intermediate, or
unstable
Stren
g
ths are described in the
next section.