SN54BCT8245A, SN74BCT8245A

SCAN TEST DEVICES

WITH OCTAL BUS TRANSCEIVERS

SCBS043E – MAY 1990 – REVISED JULY 1996

4

POST OFFICE BOX 655303

Terminal Functions

TERMINAL

NAME

DESCRIPTION

A1–A8

A-bus I/O ports. See function table for normal-mode logic. Internal pullups force these I/O ports to a high level if left

unconnected.

B1–B8

B-bus I/O ports. See function table for normal-mode logic. Internal pullups force these I/O ports to a high level if left

unconnected.

DIR

Normal-function direction-control input. See function table for normal-mode logic. An internal pullup forces DIR to a high

level if left unconnected.

GND

Ground

OE

Normal-function output-enable input. See function table for normal-mode logic. An internal pullup forces OE to a high level

if left unconnected.

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. An internal pullup forces

TCK to a high level if left unconnected.

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. An internal pullup forces TDO to a high level when it is not active

and is not driven from an external source.

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. TMS also provides the optional test reset

signal of IEEE Standard 1149.1-1990. This is implemented by recognizing a third logic level, double high (VIHH), at TMS.

VCC

Supply voltage