TECHNICAL DATA
IN74AC251
8-Input Data Selector/Multiplexer
with 3-State Outputs
High-Speed Silicon-Gate CMOS
The IN74AC251 is identical in pinout to the LS/ALS251,
HC/HCT251. The device inputs are compatible with standard CMOS
outputs; with pullup resistors, they are compatible with LS/ALS
outputs.
The device selects one of the eight binary Data Inputs, as
determined by the Address Inputs. The Output Enable pin must be at a
low level for the selected data to appear at the outputs. If Output
Enable is high, the Y and the Y outputs are in the high-impedance
state. This 3-State feature allows the IN74AC251 to be used in bus-
oriented systems.
•
Outputs Directly Interface to CMOS, NMOS, and TTL
•
Operating Voltage Range: 2.0 to 6.0 V
•
Low Input Current: 1.0
µA;
0.1
µA
@ 25°C
•
High Noise Immunity Characteristic of CMOS Devices
•
Outputs Source/Sink 24 mA
ORDERING INFORMATION
IN74AC251N Plastic
IN74AC251D SOIC
T
A
= -40° to 85° C for all
packages
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
A2
X
L
L
L
L
H
PIN 16 =V
CC
PIN 8 = GND
H
H
A1
X
L
L
H
H
L
L
H
A0
X
L
H
L
H
L
H
L
Output
Enable
H
L
L
L
L
L
L
L
Outputs
Y
Z
D0
D1
D2
D3
D4
D5
D6
Y
Z
D0
D1
D2
D3
D4
D5
D6
H H
H
L
D7
D7
D0,D1...D7=the level of the respective D
input
Z = high-impedance state
X = don’t care
336
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