SN74AS856 Datasheet, PDF (1/9 Pages) Texas Instruments – 8-BIT UNIVERSAL TRANSCEIVER PORT CONTROLLERS

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SN54AS856, SN74AS856
8-BIT UNIVERSAL TRANSCEIVER PORT CONTROLLERS
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SDAS032A − DECEMBER 1983 − REVISED MARCH 1985
• Package Options Include Plastic Small
Outline Packages, Both Plastic and
Ceramic Chip Carriers, and Standard
SN54AS856 . . . JT PACKAGE
SN74AS856 . . . DW OR NT PACKAGE
(TOP VIEW)
Plastic and Ceramic 300-mil DIPs
• Buffered 3-State Outputs Drive Bus Lines
Directly
• Cascadable to n-Bits
• Eight Selectable Transceiver/Port
OEB 1
OEA 2
MODE 3
A1 4
A2 5
24 V_CC
23 CLK
22 SERIN
21 B1
20 B2
Functions:
− B to A
− Register to A and/or B
− Off-Line Shifts (A and B Ports in
High-Impedance State)
− Shifted to A and/or B
• Particularly Suitable for Use in Diagnostics
A3 6
A4 7
A5 ⁸
A6 ⁹
A7 ¹⁰
A8 ¹¹
GND ¹²
19 B3
18 B4
17 _B5
16 _B6
15 _B7
14 _B8
13 _Q8
Analysis Circuitry
• Serial Register Provides:
− Parallel Storage of Either A or B input
Data
SN54AS856 . . . FK PACKAGE
SN74AS856 . . . FN PACKAGE
(TOP VIEW)
− Serial Transmission of Data from Either
A or B Port
− Readback Mode B to A
• Dependable Texas Instruments Quality and
Reliability
4 3 2 1 28 27 26
A1 ⁵
25 B1
A2 ⁶
24 B2
description
A3 7
NC 8
23 B3
22 NC
The ’AS856 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
A4 9
21 B4
A5 10
20 B5
A6 11
19 B6
12 13 14 15 16 17 18
performing eight selectable transceiver or port
functions, depending on the state of the three
control lines OEA, OEB, and MODE. These
functions include: transferring data from port A to
NC − No internal connection
port B or vice versa (i.e., the transceiver function),
serial shifting data to either or both ports, and
performing off-line shifts (with A and B ports active
as transceivers in a high-impedance state).
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 ’AS856 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 SN54AS856 is characterized for operation over the full military temperature range of −55°C to 125°C. The
SN74AS856 is characterized for operation from 0°C to 70°C.
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.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Copyright  1985, Texas Instruments Incorporated
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