HD74LS155 Datasheet, PDF (2/7 Pages) Hitachi Semiconductor – Dual 2-line-to-4-line Decoders/Demultiplexers

HD74LS155
Function Table
• 2-line-to-4-line Decoder / 1-line-to-4-line Demultiplexer
Inputs
Outputs
Select
Strobe
Data
B
A
1G
1C
1Y₀
1Y₁
1Y₂
1Y₃
X
X
H
X
H
H
H
H
L
L
L
H
L
H
H
H
L
H
L
H
H
L
H
H
H
L
L
H
H
H
L
H
H
H
L
H
H
H
H
L
X
X
X
L
H
H
H
H
Inputs
Outputs
Select
Strobe
Data
B
A
2G
2C
2Y₀
2Y₁
2Y₂
2Y₃
X
X
H
X
H
H
H
H
L
L
L
L
L
H
H
H
L
H
L
L
H
L
H
H
H
L
L
L
H
H
L
H
H
H
L
L
H
H
H
L
X
X
X
H
H
H
H
H
• 3-line-to-8-line Decoder / 1-line-to-8-line Demultiplexer
Inputs
Outputs
Select
Strobe
Data
0
1
2
3
4
5
6
7
C
B
A
G
2Y₀
2Y₁
2Y₂
2Y₃
1Y₀
1Y₁
1Y₂
1Y₃
X
X
X
H
H
H
H
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
H
H
L
L
H
L
H
L
H
H
H
H
H
H
L
H
L
L
H
H
L
H
H
H
H
H
L
H
H
L
H
H
H
L
H
H
H
H
H
L
L
L
H
H
H
H
L
H
H
H
H
L
H
L
H
H
H
H
H
L
H
H
H
H
L
L
H
H
H
H
H
H
L
H
H
H
H
L
H
H
H
H
H
H
H
L
Notes: 1. C ; input 1C and 2C connected together
2. G ; inputs 1G and 2G connected together
3. H ; high level, L ; low level, X ; irrelevant
Rev.2.00, Feb.18.2005, page 2 of 6