SN54ABT8543, SN74ABT8543

SCAN TEST DEVICES WITH

OCTAL REGISTERED BUS TRANSCEIVERS

SCBS120E – AUGUST 1991 – REVISED JULY 1996

4

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

Terminal Functions

TERMINAL

NAME

DESCRIPTION

A1–A8

Normal-function A-bus I/O ports. See function table for normal-mode logic.

B1–B8

Normal-function B-bus I/O ports. See function table for normal-mode logic.

CEAB, CEBA

Normal-function chip-enable inputs. See function table for normal-mode logic.

GND

Ground

LEAB, LEBA

Normal-function latch-enable inputs. See function table for normal-mode logic.

OEAB, OEBA

Normal-function output-enable inputs. See function table for normal-mode logic.

TCK

Test clock. One of four terminals required by IEEE Standard 1149.1-1990. Test operations of the device are synchronous to

TCK. Data is captured on the rising edge of TCK, and outputs change on the falling edge of TCK.

TDI

Test data input. One of four terminals required by IEEE Standard 1149.1-1990. TDI is the serial input for shifting data through

the instruction register or selected data register. An internal pullup forces TDI to a high level if left unconnected.

TDO

Test data output. One of four terminals required by IEEE Standard 1149.1-1990. TDO is the serial output for shifting data

through the instruction register or selected data register.

TMS

Test mode select. One of four terminals required by IEEE Standard 1149.1-1990. TMS directs the device through its TAP

controller states. An internal pullup forces TMS to a high level if left unconnected.

VCC

Supply voltage