SN54ALS137A, SN74ALS137A, SN74AS137
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
WITH ADDRESS LATCHES
SDAS203C – APRIL 1982 – REVISED JANUARY 1995
Copyright  1995, Texas Instruments Incorporated
1POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
• Combines Decoder and 3-Bit Address
Latch
• Incorporates Two Output Enables to
Simplify Cascading
• Package Options Include Plastic Small-
Outline (D) Packages, Ceramic Chip
Carriers (FK), and Standard Plastic (N) and
Ceramic (J) 300-mil DIPs

description
The SN54ALS137A, SN74ALS137A, and
SN74AS137 are 3-line to 8-line decoders/
demultiplexers with latches on the three address
inputs. When the latch-enable (LE) input is low,
the devices act as decoders/demultiplexers.
When LE goes from low to high, the address
present at the select (A, B, and C) inputs is stored
in the latches. Further address changes are
ignored as long as LE remains high. The
output-enable controls (G1 and G2) control the
outputs independently of the select or
latch-enable inputs. All of the outputs are forced
high if G1 is low or G2 is high. These devices are
ideally suited for implementing glitch-free
decoders in strobed (stored-address) applications
in bus-oriented systems.
The SN54ALS137A is characterized for operation
over the full military temperature range of –55°C
to 125°C. The SN74ALS137A and SN74AS137
are characterized for operation from 0°C to 70°C.
FUNCTION TABLE
INPUTS
OUTPUTS
ENABLE SELECT
LE G1 G2 C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
X X H X X X H H H H H H H H
X LXXXXHHHHHHHH
LHL L L L LHHHHHHH
LHLLLHHLHHHHHH
LHLLHLHHLHHHHH
LHLLHHHHHLHHHH
LHLHL LHHHHLHHH
LHLHLHHHHHHLHH
LHLHHLHHHHHHLH
LHLHHHHHHHHHHL
HHLXXX Outputs corresponding to stored address = L; all others = H
SN54ALS137A ...J PACKAGE
SN74ALS137A, SN74AS137 ...D OR N PACKAGE
(TOP VIEW)
3 2 1 20 19
910111213
4
5
6
7
8
18
17
16
15
14
Y1
Y2
NC
Y3
Y4
C
LE
NC
G2
G1
SN54ALS137A . . . FK PACKAGE
(TOP VIEW)
B A NC
Y6 Y5
Y0
Y7
GND
NC
NC – No internal connection
V
CC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
A
B
C
LE
G2
G1
Y7
GND
V
CC
Y0
Y1
Y2
Y3
Y4
Y5
Y6
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.