74HC251 Datasheet, PDF (4/7 Pages) NXP Semiconductors – 8-input multiplexer; 3-state

Philips Semiconductors
8-input multiplexer; 3-state
Product specification
74HC/HCT251
FUNCTION TABLE
INPUTS
OUTPUTS
OE
S₂
S₁
S₀
I₀
I₁
I₂
I₃
I₄
I₅
I₆
I₇
Y
Y
H
X
X
X
X
X
X
X
X
X
X
X
Z
Z
L
L
L
L
L
X
X
X
X
X
X
X
H
L
L
L
L
L
H
X
X
X
X
X
X
X
L
H
L
L
L
H
X
L
X
X
X
X
X
X
H
L
L
L
L
H
X
H
X
X
X
X
X
X
L
H
L
L
H
L
X
X
L
X
X
X
X
X
H
L
L
L
H
L
X
X
H
X
X
X
X
X
L
H
L
L
H
H
X
X
X
L
X
X
X
X
H
L
L
L
H
H
X
X
X
H
X
X
X
X
L
H
L
H
L
L
X
X
X
X
L
X
X
X
H
L
L
H
L
L
X
X
X
X
H
X
X
X
L
H
L
H
L
H
X
X
X
X
X
L
X
X
H
L
L
H
L
H
X
X
X
X
X
H
X
X
L
H
L
H
H
L
X
X
X
X
X
X
L
X
H
L
L
H
H
L
X
X
X
X
X
X
H
X
L
H
L
H
H
H
X
X
X
X
X
X
X
L
H
L
L
H
H
H
X
X
X
X
X
X
X
H
L
H
Note
1. H = HIGH voltage level
L = LOW voltage level
X = don’t care
Z = high impedance OFF-state
Fig.4 Functional diagram.
December 1990
Fig.5 Logic diagram.
4