Datasheet

74VHC153 Dual 4-Input Multiplexer
©1993 Fairchild Semiconductor Corporation www.fairchildsemi.com
74VHC153 Rev. 1.2 2
Logic Symbols
IEEC/IEC
Functional Description
The VHC153 is a dual 4-input multiplexer. It can select two
bits of data from up to four sources under the control of the
common Select inputs (S
0
, S
1
). The two 4-input multi-
plexer circuits have individual active-LOW Enables (E
a
,
E
b
) which can be used to strobe the outputs indepen-
dently. When the Enables (E
a
, E
b
) are HIGH, the corre-
sponding outputs (Z
a
, Z
b
) are forced LOW. The VHC153 is
the logic implementation of a 2-pole, 4-position switch,
where the position of the switch is determined by the logic
levels supplied to the Select inputs. The logic equations for
the outputs are shown below.
Z
a
= E
a
• (I
0a
• S
1
• S
0
+ I
1a
• S
1
• S
0
+ I
2a
• S
1
• S
0
+ I
3a
• S
1
• S
0
)
Z
b
= E
b
• (I
0b
• S
1
• S
0
+ I
1b
• S
1
• S
0
+ I
2b
• S
1
• S
0
+ I
3b
• S
1
• S
0
)
Truth Table
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Select
Inputs (a or b) OutputInputs
S
0
S
1
E I
0
I
1
I
2
I
3
Z
XXHXXXX L
LLLLXXX L
LLLHXXX H
HLLXLXX L
HLLXHXX H
LHLXXLX L
LHLXXHX H
HHLXXXL L
HHLXXXH H