SN54ALS137A, SN74ALS137A, SN74AS137

3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS

WITH ADDRESS LATCHES

SDAS203C – APRIL 1982 – REVISED JANUARY 1995

Copyright

1

POST OFFICE BOX 655303

Latch

Simplify Cascading

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

OUTPUTS

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

LX

X

XX

H

HH

HH

HH

H

L

H

L

L

L

L

L

H

H

H

H

H

H

H

L

HL

L

LH

H

L

H

HH

HH

H

L

HL

L

HLH

H

L

HH

HH

H

L

HL

L

HH

H

HH

L

H

HH

H

L

H

L

H

L

L

H

H

H

H

L

H

H

H

L

HL

H

LH

H

HH

HH

L

H

H

L

HL

H

HLH

HH

HH

H

L

H

L

HL

H

HH

H

HH

HH

HH

L

H

H

L

X

X

X

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

910 11 12 13

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)

NC – No internal connection

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

A

B

C

LE

G2

G1

Y7

GND

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.