SN54AS877, SN74AS877

8BIT UNIVERSAL TRANSCEIVER PORT CONTROLLERS

SDAS234 − D2661, DECEMBER 1982 − REVISED AUGUST 1985

POST OFFICE BOX 655303

Copyright

1

Outline Packages, Both Plastic and

Ceramic Chip Carriers, and Standard

Plastic and Ceramic 300-mil DIPs

Directly

Functions:

A to B or B to A

Register to A or Register to B

Shifted to A or Shifted to B

Off-Line Shifts (A and B Ports in

High-Impedance State)

Register Clear

Analysis Circuitry

Parallel Storage of Either A or B Input

Data

Serial Transmission of Data from Either

A or B Port

Reliability

description

The ’AS877 features two 8-bit I/O ports (A1-A8

and B1-B8), an 8-bit parallel-load, serial-in,

parallel-out shift register, and control logic. With

these

features,

this

device

is

capable

of

performing eight selectable transceiver or port

functions, depending on the state of the three

select lines S0, S1, and S2. These functions

include: transferring data from port A to port B or

vice

versa

(i.e.,

the

transceiver

function),

transferring data from the register to either port,

serial shifting data to either port, performing off-line shifts (with A and B ports in high-impedance state), and

clearing the register. Synchronous parallel loading of the internal register can be accomplished from either port

on the positive transition of the clock while serially shifting data in via the SERIN input. The ’AS877 is ideally

suited for applications needing signature-analysis circuitry to enhance system verification and/or fault analysis.

All serial data is shifted right. All outputs are buffer-type outputs designed specifically to drive bus lines directly

and all are 3-state except for Q8, which is a totem-pole output.

The SN54AS877 is characterized for operation over the full military temperature range of −55

°C to 125°C. The

SN74AS877 is characterized for operation from 0

°C to 70°C.

1

2

3

4

5

6

7

8

9

10

11

12

24

23

22

21

20

19

18

17

16

15

14

13

S0

S1

S2

A1

A2

A3

A4

A5

A6

A7

A8

GND

CLK

SERIN

B1

B2

B3

B4

B5

B6

B7

B8

Q8

SN54AS877 . . . JT PACKAGE

SN74AS877 . . . DW OR NT PACKAGE

(TOP VIEW)

32 1

13 14

5

6

7

8

9

10

11

B1

B2

B3

NC

B4

B5

B6

A1

A2

A3

NC

A4

A5

A6

4

15 16 17 18

SN54AS877 . . . JT PACKAGE

SN74AS877 . . . DW OR NT PACKAGE

(TOP VIEW)

28 27 26

25

24

23

22

21

20

19

12

NC − No internal connection

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.