Page 139 - Bebop to The Boolean Boogie An Unconventional Guide to Electronics Fundamentals, Components, and Processes

120 ChapterEIeven

Figure 1 1-1 4. Waveform for a D-type latch with active-high enable

D-Type Flip-flops
In the case of a D-type flip-flop (which may also be referred to as a register),

the data appears to be loaded when a transition, or edge, occurs on the clock
input, which is therefore said to be edge-sensitive (the reason we say “appears to
zl occurs” is discussed in
be loaded when an edge
D flip-flop
rl-l
the sidebar on the next
clock b page). A transition from

Otol isknownasa
rising-edge or a positive-
u edge, while a transition
from I to O is known
as a falling-edge or a
negative-edge. A D-type
flip-flop’s clock input
may be positive-edge or
negative-edge triggered
(Figure 11-15).
The chevrons
Positive - Edge Triggered Negative - Edge Triggered
(arrows ‘5”) associated

Figure 1 1-1 5. Positive-edge and with the clock inputs
negativeedge D-type flip-flops on the symbols indicate