HIT HD74HC158, HD74HC157 Datasheet
HD74HC157/HD74HC158
Quad. 2-to-1-line Data Selectors/Multiplexers
(with noninverted outputs)
Quad. 2-to-1-line Data Selectors/Multiplexers
(with inverted outputs)
Description
These devices each consist of four 2-input digital multiplexers with common select and strobe inputs. On
the HD74HC157, when the strobe input is at logical “L” the four outputs assume the values as selected
from the inputs. When the strobe input is at a logical “H” the outputs assume logical “L”. The
HD74HC158 operates in the same manner, except that its outputs are inverted. Select decoding is done
internally resulting in a single select input only. If enabled, the select input determines whether the A or B
inputs get routed to their corresponding Y outputs.
Features
• High Speed Operation: tpd (Data to Output) = 12 ns typ (CL = 50 pF)
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: VCC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)
Function Table
Inputs Output Y
Strobe Select A B HC157 HC158
HX X X L H
LLLXLH
LL H X H L
LHXLLH
LHXHHL
HD74HC157/HD74HC158
Pin Arrangement
Select
Inputs
Output
1A
1B
1Y
V
1
2
3
4
1A
1B
1Y
S
S
4A
4B
16
15
14
13
CC
Strobe
4A
Inputs
4B
Logic Diagram
HD74HC157
Inputs
Output
2A
2B
2Y
GND
12
11
10
1Y
2Y
3Y
Output
4Y
3A
Inputs
3B
3Y
Output
9
1A
1B
2A
2B
3A
3B
2A
2B
2Y
3Y
(Top view)
4Y
3A
3B
5
6
7
8
4A
4B
Select
Strobe
2
4Y
HD74HC158
HD74HC157/HD74HC158
Select
Strobe
1A
1B
2A
2B
3A
3B
4A
4B
1Y
2Y
3Y
4Y
3
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