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.
ORDERING INFORMATION
IN74AC251N Plastic
IN74AC251D SOIC
TA = -40° to 85° C for all packages
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•
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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
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Outputs Source/Sink 24 mA
PIN ASSIGNMENT
LOGIC DIAGRAM
FUNCTION TABLE
Inputs
Outputs
A2 A1 A0 Output
Enable
Y
Y
X
L
X
L
X
L
H
L
L
L
L
L
L
L
L
Z
Z
D0
D1
D2
D3
D4
D5
D6
D7
D0
D1
D2
D3
D4
D5
D6
D7
L
L
H
L
L
H
H
L
L
H
L
H
H
H
H
L
H
L
PIN 16 =VCC
PIN 8 = GND
H
H
H
D0,D1...D7=the level of the respective D
input
Z = high-impedance state
X = don’t care
Rev. 00
IKSEMICON [ IK SEMICON CO., LTD ]
