SN54ABT8543, SN74ABT8543

SCAN TEST DEVICES WITH

OCTAL REGISTERED BUS TRANSCEIVERS

SCBS120E – AUGUST 1991 – REVISED JULY 1996

2

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

description (continued)

Data flow in each direction is controlled by latch-enable (LEAB and LEBA), chip-enable (CEAB and CEBA), and

output-enable (OEAB and OEBA) inputs. For A-to-B data flow, the device operates in the transparent mode

when LEAB and CEAB are both low. When either LEAB or CEAB is high, the A data is latched. The B outputs

are active when OEAB and CEAB are both low. When either OEAB or CEAB is high, the B outputs are in the

high-impedance state. Control for B-to-A data flow is similar to that for A-to-B, but uses LEBA, CEBA, and OEBA.

In the test mode, the normal operation of the SCOPE

™ registered bus transceiver is inhibited and the test

circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry

performs boundary-scan test operations as described in IEEE Standard 1149.1-1990.

Four dedicated test pins control the operation of the test circuitry: test data input (TDI), test data output (TDO),

test mode select (TMS), and test clock (TCK). Additionally, the test circuitry performs other testing functions

such as parallel-signature analysis (PSA) on data inputs and pseudo-random pattern generation (PRPG) from

data outputs. All testing and scan operations are synchronized to the TAP interface.

The SN54ABT8543 is characterized for operation over the full military temperature range of –55

°C to 125°C.

The SN74ABT8543 is characterized for operation from –40

°C to 85°C.

FUNCTION TABLE†

(normal mode, each register)

INPUTS

OUTPUT

CEAB

OEAB

LEAB

A

B

L

L

L

L

L

L

LL

H

H

L

LH

X

B0‡

L

HX

X

Z

H

X

X

X

Z

† A-to-B data flow is shown. B-to-A data flow is similar but

uses CEBA, OEBA, and LEBA.

‡ Output level before the indicated steady-state input

conditions were established