74act18823 Fairchild Semiconductor, 74act18823 Datasheet - Page 2

• Manufacturer Part Number: 74act18823
• Description: 18-bit D-type Flip-flop With 3-state Outputs
• Manufacturer: Fairchild Semiconductor

www.fairchildsemi.com
Functional Description
The ACT18823 consists of eighteen D-type edge-triggered
flip-flops. These have 3-STATE outputs for bus systems
organized with inputs and outputs on opposite sides. The
device is byte controlled with each byte functioning identi-
cally, but independent of the other. The control pins can be
shorted together to obtain full 16-bit operation. The follow-
ing description applies to each byte. The buffered clock
(CP
flip-flops within that byte. The flip-flops will store the state
of their individual D inputs that meet set-up and hold time
requirements on the LOW-to-HIGH CP
OE
outputs. When OE
ance state. Operation of the OE
state of the flip-flops. In addition to the Clock and Output
Enable pins, there are Clear (CLR
(EN
ing in high performance systems.
When CLR
LOW. When CLR
flip-flops. When EN
ferred to the outputs on the LOW-to-HIGH clock transition.
When the EN
regardless of the data or clock input transitions.
Logic Diagrams
n
n
n
) and buffered Output Enable (OE
LOW, the contents of the flip-flops are available at the
) pins. These devices are ideal for parity bus interfac-
n
is LOW and OE
n
is HIGH, the outputs do not change state,
n
n
is HIGH, data can be entered into the
n
is HIGH, the outputs go to the imped-
is LOW, data on the inputs is trans-
n
n
is LOW, the outputs are
input does not affect the
n
) and Clock Enable
n
) are common to all
n
transition. With
Byte 2 (9:17)
Byte 1 (0:8)
2
Function Table
(Note 1)
H HIGH Voltage Level
L LOW Voltage Level
X Immaterial

Z High Impedance
NC No Change
Note 1: The table represents the logic for one byte. The two bytes are inde-
pendent of each other and function identically.
OE CLR EN
H
H
H
H
H
H
L
L
L
L
LOW-to-HIGH Transition
X
X
H
H
H
H
H
H
L
L
Inputs
X
X
H
H
L
L
L
L
L
L
CP






X
X
X
X
I
H
X
X
X
X
H
H
L
L
L
n
Internal Output
NC
NC
Q
H
H
H
L
L
L
L
L
NC
O
H
Z
Z
Z
L
Z
Z
Z
L
n
High Z
High Z
Clear
Clear
Hold
Hold
Load
Load
Load
Load
Function