SN54ABTH18504A, SN54ABTH182504A, SN74ABTH18504A, SN74ABTH182504A

SCAN TEST DEVICES WITH

20-BIT UNIVERSAL BUS TRANSCEIVERS

SCBS165C – AUGUST 1993 – REVISED JULY 1996

5

POST OFFICE BOX 655303

Terminal Functions

TERMINAL NAME

DESCRIPTION

A1–A20

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

B1–B20

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

CLKAB, CLKBA

Normal-function clock inputs. See function table for normal-mode logic.

CLKENAB, CLKENBA

Normal-function clock enables. See function table for normal-mode logic.

GND

Ground

LEAB, LEBA

Normal-function latch enables. See function table for normal-mode logic.

OEAB, OEBA

Normal-function output enables. See function table for normal-mode logic. An internal pullup at each terminal

forces the terminal 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.

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