TL/F/6549
DM54155/DM74155 Dual 2-Line to 4-Line Decoders/Demultiplexers
February 1993
DM54155/DM74155 Dual 2-Line to 4-Line
Decoders/Demultiplexers
General Description
These TTL circuits feature dual 1-line-to-4-line demultiplex-
ers with individual strobes and common binary-address in-
puts in a single 16-pin package. When both sections are
enabled by the strobes, the common address inputs se-
quentially select and route associated input data to the ap-
propriate output of each section. The individual strobes per-
mit activating or inhibiting each of the 4-bit sections as de-
sired. Data applied to input C1 is inverted at its outputs and
data applied at C2 is true through its outputs. The inverter
following the C1 data input permits use as a 3-to-8-line de-
coder, or 1-to-8-line demultiplexer, without external gating.
Input clamping diodes are provided on these circuits to mini-
mize transmission-line effects and simplify system design.
Features
Y
Applications:
Dual 2-to-4-line decoder
Dual 1-to-4-line demultiplexer
3-to-8-line decoder
1-to-8-line demultiplexer
Y
Individual strobes simplify cascading for decoding or
demultiplexing larger words
Y
Input clamping diodes simplify system design
Connection Diagram and Function Tables
Dual-In-Line Package
TL/F/6549–1
Order Number DM54155J, DM54155W or DM74155N
See NS Package Number J16A, N16A or W16A
²
C
e
inputs C1 and C2 connected together
³
G
e
inputs G1 and G2 connected together
H
e
high level, L
e
low level, X
e
don’t care
2-Line-to-4-Line Decoder or
1-Line-to-4-Line Demultiplexer
Inputs Outputs
Select Strobe Data
B A G1 C1 1Y0 1Y1 1Y2 1Y3
XX H X HHHH
LL L H LHHH
LH L HHLHH
HL L H HHLH
HH L H HHHL
XX X L HHHH
Inputs Outputs
Select Strobe Data
B A G2 C2 2Y0 2Y1 2Y2 2Y3
XX H X HHHH
LL L L LHHH
LH L L HLHH
HL L L HHLH
HH L L HHHL
XX X H HHHH
3-Line-to-8-Line Decoder or
1-Line-to-8-Line Demultiplexer
Inputs Outputs
Select
Strobe
(0) (1) (2) (3) (4) (5) (6) (7)
Or Data
C
²
BA G
³
2Y0 2Y1 2Y2 2Y3 1Y0 1Y1 1Y2 1Y3
XXX H HHHHHHHH
LLL L LHHHHHHH
LLH L HLHHHHHH
LHL L HHLHHHHH
LHH L HHHLHHHH
HLL L HHHHLHHH
HLH L HHHHHLHH
HHL L HHHHHHLH
HHH L HHHHHHHL
C
1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.