SN54F621, SN74F621

OCTAL BUS TRANSCEIVERS

WITH OPEN-COLLECTOR OUTPUTS

SDFS004B – D2932, MARCH 1987 – REVISED OCTOBER 1993

Copyright

2–1

POST OFFICE BOX 655303

Small-Outline Packages, Ceramic Chip

Carriers, and Standard Plastic and Ceramic

300-mil DIPs

description

These octal bus transceivers are designed for

asynchronous

communication

between

data

buses. The control function implementation allows

for maximum flexibility in timing.

These devices allow data transmission from the A

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

depending upon the logic levels at the output

enable (OEAB and OEBA) inputs.

The output-enable inputs can be used to disable

the device so that the buses are effectively

isolated. The dual-enable configuration gives the

transceivers the capability of storing data by

simultaneously enabling OEAB and OEBA. Each

output reinforces its input in this configuration.

When both OEAB and OEBA are enabled and all

other data sources to the two sets of bus lines are

at high impedance, both sets of bus lines (16 in all)

will remain at their last states.

The SN54F621 is characterized for operation over

the full military temperature range of – 55

°C to

125

°C. The SN74F621 is characterized for

operation from 0

°C to 70°C.

FUNCTION TABLE

INPUTS

OPERATION

OEBA

OEAB

OPERATION

L

L

B data to A bus

L

H

B data to A bus,

A data to B bus

H

L

Isolation

H

H

A data to B bus

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

OEAB

A1

A2

A3

A4

A5

A6

A7

A8

GND

OEBA

B1

B2

B3

B4

B5

B6

B7

B8

SN54F621 ...J PACKAGE

SN74F621 . . . DW OR N PACKAGE

(TOP VIEW)

3

2

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

SN54F621 . . . FK PACKAGE

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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.