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74F823
Unit Loading/Fan Out
Functional Description
The 74F823 device consi sts of nine D-type edge-trigg ered
flip-flops. It has 3-STATE true outputs and is organized in
broadside pinning. T he buffered Clock (CP) and buffere d
Output Enable (OE
) are common to all flip-flops. The flipflops will store the state of their individual D inputs that
meet the setup and ho ld times requi rements on the L OWto-HIGH CP transition. With the OE
LOW the contents of
the flip-flops are av ailable at the outputs. W hen the OE
is
HIGH, the outputs go to th e high impeda nce state. Op eration of the OE
input does not affect t he state of the flipflops. In addition to the Clock and Outp ut Enable pins, the
74F823 has Clear (CLR
) and Clock Enable (EN) pins.
When the CLR
is LOW an d the OE is LOW, the outputs are
LOW. When CLR
is HIGH, data can be entered into the flip-
flops. When EN
is LOW, data on the inputs is transferred to
the outputs on the LOW-to-HIGH clock transition . When
the EN
is HIGH, the outputs do not change state regardless of the data or clock inputs transitio ns. This device is
ideal for parity bus interfacing in high performance systems.
Function Table
L = LOW Voltage Level
H = HIGH Voltage Level
X = Immaterial
Z = High Impedan ce
= LOW-to-HIGH Transition
NC = No Change
Logic Diagram
Please note that this diagram is provided o nly f or t he understanding of lo gic operations and should not be used to estimate propagation delays.
Pin Names Description
U.L.
Input I
IH/IIL
HIGH/LOW
Output I
OH/IOL
D0–D
8
Data Inputs 1.0/1.0 20 µA/−0.6 mA
OE
Output Enable Input 1.0/1.0 20 µA/−0.6 mA
CLR
Clear 1.0/1.0 20 µA/−0.6 mA
CP Clock Input 1.0/2.0 20 µA/−1.2 mA
EN
Clock Enable 1.0/1.0 20 µA/−0.6 mA
O
0–O8
3-STATE Outputs 150/40 (33.3) −3 mA/24 mA (20 mA)
Inputs Internal Output
Function
OE
CLR EN CP D Q O
HHLHXNC ZHold
HHLLXNC ZHold
H H H X X NC Z Hold
LHHXXNC NCHold
H L X X X H Z Clear
L L X X X H L Clear
HHL
H H Z Load
HHL
H L Z Load
LHL
L H L Data Available
LHL
H L H Data Available
L H L H X NC NC No Change in Data
L H L L X NC NC No Change in Data