SN54ALS652, SN54ALS653, SN54AS651, SN54AS652

SN74ALS651A, SN74ALS652A, SN74ALS653, SN74ALS654, SN74AS651, SN74AS652

OCTAL BUS TRANSCEIVERS AND REGISTERS WITH 3-STATE OUTPUTS

SDAS066F – DECEMBER 1983 – REVISED OCTOBER 1996

1

POST OFFICE BOX 655303

and B Buses

Outputs to A Bus

Small-Outline (DW) Packages, Ceramic

Chip Carriers (FK), and Standard Plastic

(NT) and Ceramic (JT) 300-mil DIPs

DEVICE

A OUTPUT

B OUTPUT

LOGIC

SN74ALS651A,

’AS651

3 State

3 State

Inverting

SN54ALS652,

SN74ALS652A,

’AS652

3 State

3 State

True

’ALS653

Open Collector

3 State

Inverting

SN74ALS654

Open Collector

3 State

True

description

These devices consist of bus-transceiver circuits,

D-type flip-flops, and control circuitry arranged for

multiplexed transmission of data directly from the

data bus or from the internal storage registers.

Output-enable (OEAB and OEBA) inputs are

provided to control the transceiver functions.

Select-control (SAB and SBA) inputs are provided

to select real-time or stored data transfer. The

circuitry used for select control eliminates the

typical decoding glitch that occurs in a multiplexer

during the transition between stored and real-time

data. A low input level selects real-time data, and

a high input level selects stored data. Figure 1

illustrates the four fundamental bus-management functions that can be performed with the octal bus

transceivers and registers.

Data on the A or B data bus, or both, can be stored in the internal D-type flip-flops by low-to-high transitions at

the appropriate clock (CLKAB or CLKBA) terminals, regardless of the select- or output-control terminals. When

SAB and SBA are in the real-time transfer mode, it is possible to store data without using the internal D-type

flip-flops by simultaneously enabling OEAB and OEBA. In this configuration, each output reinforces its input.

When all other data sources to the two sets of bus lines are at high impedance, each set of bus lines remains

at its last state.

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.

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.

NC – No internal connection

SN54ALS’, SN54AS’ . . . FK PACKAGE

(TOP VIEW)

SN54ALS’, SN54AS’ . . . JT PACKAGE

SN74ALS’, SN74AS’ . . . DW OR NT PACKAGE

(TOP VIEW)

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

CLKAB

SAB

OEAB

A1

A2

A3

A4

A5

A6

A7

A8

GND

CLKBA

SBA

OEBA

B1

B2

B3

B4

B5

B6

B7

B8

32 1

13 14

5

6

7

8

9

10

11

OEBA

B1

B2

NC

B3

B4

B5

A1

A2

A3

NC

A4

A5

A6

4

15 16 17 18

28 27 26

25

24

23

22

21

20

19

12