Datasheet

December 1990 4
Philips Semiconductors Product specification
8-input multiplexer; 3-state 74HC/HCT251
FUNCTION TABLE
Note
1. H = HIGH voltage level
L = LOW voltage level
X = don’t care
Z = high impedance OFF-state
INPUTS OUTPUTS
OE S
2
S
1
S
0
I
0
I
1
I
2
I
3
I
4
I
5
I
6
I
7
YY
HXXXXXXXXXXXZZ
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
L
H
X
X
X
X
L
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
H
L
H
L
L
H
L
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
H
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
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
H
X
X
X
X
X
X
X
X
H
L
H
L
L
H
L
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
H
L
H
L
L
H
L
H
Fig.4 Functional diagram. Fig.5 Logic diagram.