Philips Semiconductors
Product specification
8-input multiplexer; 3-state
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
L
L
L
L
L
L
L
L
L
H
H
L
H
X
X
X
X
L
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
H
H
L
L
L
L
L
L
L
L
H
H
H
H
L
L
H
H
X
X
X
X
X
X
X
X
L
H
X
X
X
X
L
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
H
H
L
L
L
L
H
H
H
H
L
L
L
L
L
L
H
H
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
H
X
X
X
X
L
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
H
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
H
H
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
H
X
X
X
X
L
H
L
H
L
L
H
L
H
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
NXP [ NXP ]
