SN74ABT18502

SCAN TEST DEVICE

WITH 18-BIT REGISTERED BUS TRANSCEIVER

SCBS753 – FEBRUARY 2002

4

POST OFFICE BOX 655303

Terminal Functions

PIN NAME

DESCRIPTION

GND

Ground

TCK

Test clock. One of four pins required by IEEE Std 1149.1-1990. Test operations of the device are synchronous to the test

clock. 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 pins required by IEEE Std 1149.1-1990. TDI is the serial input for shifting data through the

instruction register (IR) or selected data register (DR). An internal pullup forces TDI to a high level if left unconnected.

TDO

Test data output. One of four pins required by IEEE Std 1149.1-1990. TDO is the serial output for shifting data through

the IR or selected DR.

TMS

Test mode select. One of four pins required by IEEE Std 1149.1-1990. The TMS input directs the device through its TAP

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

VCC

Supply voltage

1A1–1A9,

2A1– 2A9

Normal-function A-bus I/O ports (see function table for normal-mode logic)

1B1–1B9,

2B1– 2B9

Normal-function B-bus I/O ports (see function table for normal-mode logic)

1CLKAB, 1CLKBA,

2CLKAB, 2CLKBA

Normal-function clock inputs (see function table for normal-mode logic)

1LEAB, 1LEBA,

2LEAB, 2LEBA

Normal-function latch enables (see function table for normal-mode logic)

1OEAB, 1OEBA,

2OEAB, 2OEBA

Normal-function output enables (see function table for normal-mode logic)