SN54ALS640B, SN54AS640, SN74ALS640B, SN74AS640

OCTAL BUS TRANSCEIVERS

WITH 3-STATE OUTPUTS

SDAS122A – DECEMBER 1983 – REVISED JANUARY 1995

Copyright

1

POST OFFICE BOX 655303

High-Density 20-Pin Packages

Small-Outline (DW) Packages, Ceramic

Chip Carriers (FK), and Standard Plastic (N)

and Ceramic (J) 300-mil DIPs

description

These octal bus transceivers are designed for

asynchronous two-way communication between

data buses. These devices transmit data from the

A bus to the B bus or from the B bus to the A bus,

depending upon the level at the direction-control

(DIR) input. The output-enable (OE) input can be

used to disable the device so that the buses are

effectively isolated.

The -1 version of the SN74ALS640B is identical to

the

standard

version,

except

that

the

increased to 48 mA. There is no -1 version of the

SN54ALS640B.

The

SN54ALS640B

and

SN54AS640

are

characterized for operation over the full military

temperature range of – 55

°C to 125°C. The

SN74ALS640B

and

SN74AS640

are

characterized for operation from 0

°C to 70°C.

FUNCTION TABLE

INPUTS

OPERATION

OE

DIR

OPERATION

L

L

B data to A bus

L

HA data to B bus

H

X

Isolation

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

DIR

A1

A2

A3

A4

A5

A6

A7

A8

GND

OE

B1

B2

B3

B4

B5

B6

B7

B8

SN54ALS640B, SN54AS640 ...J PACKAGE

SN74ALS640B, SN74AS640 . . . DW OR N PACKAGE

(TOP VIEW)

32

1 20 19

9 10 11 12 13

4

5

6

7

8

18

17

16

15

14

B1

B2

B3

B4

B5

A3

A4

A5

A6

A7

SN54ALS640B, SN54AS640 . . . FK PACKAGE

(TOP VIEW)

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.