SN54F138, SN74F138

3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS

SDFS051B – MARCH 1987 – REVISED JULY 1996

1

POST OFFICE BOX 655303

Memory Decoders and Data Transmission

Systems

Simplify Cascading and/or Data Reception

Small-Outline Packages, Ceramic Chip

Carriers, and Standard Plastic and Ceramic

300-mil DIPs

description

The

′F138 is designed to be used in

high-performance memory-decoding or data-

routing

applications

requiring

very

short

propagation delay times. In high-performance

memory systems, these decoders can be used to

minimize the effects of system decoding. When

employed with high-speed memories utilizing a

fast enable circuit, the delay times of this decoder

and the enable time of the memory are usually

less than the typical access time of the memory.

This means that the effective system delay

introduced by the decoder is negligible.

The conditions at the binary-select inputs and the

three enable inputs select one of eight output

lines. Two active-low and one active-high enable

inputs reduce the need for external gates or

inverters when expanding. A 24-line decoder can

be implemented without external inverters and a 32-line decoder requires only one inverter. An enable input can

be used as a data input for demultiplexing applications.

The SN54F138 is characterized for operation over the full military temperature range of – 55

°C to 125°C. The

SN74F138 is characterized for operation from 0

°C to 70°C.

Copyright

© 1996, Texas Instruments Incorporated

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.

SN54F138 ...J PACKAGE

SN74F138 ...D OR N PACKAGE

(TOP VIEW)

SN54F138 . . . FK PACKAGE

(TOP VIEW)

32

1 20 19

910 11 12 13

4

5

6

7

8

18

17

16

15

14

Y1

Y2

NC

Y3

Y4

C

G2A

NC

G2B

G1

NC – No internal connection

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

A

B

C

G2A

G2B

G1

Y7

GND

Y0

Y1

Y2

Y3

Y4

Y5

Y6

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.