PRELIMINARY

This document contains information on a product under development at Advanced Micro Devices. The information

is intended to help you evaluate this product. AMD reserves the right to change or discontinue work on this proposed

product without notice.

Publication# 21173

Rev: B Amendment/+2

Issue Date: April 1997

Am79C989

Quad Ethernet Switching Transceiver (QuEST™)

DISTINCTIVE CHARACTERISTICS

s Four independent 10BASE-T transceivers

compliant with the IEEE 802.3 standard

s Four digital Manchester Encode/Decode

(MENDEC) units

s On-chip filtering enables FCC EMI compliance

without external filters or common mode

chokes

s Automatic polarity Correction and Detection on

10BASE-T receivers

s Optional Attachment Unit Interface (AUI) for

non-10BASE-T transceivers

s 10BASE-T Extended Distance option

accommodate lines longer than 100 meters

s Quad AMD Switching Interface (QuASI™)

interface reduces overall pin count

s Half-Duplex and Full-Duplex operation

s Auto-Negotiation compliant with IEEE 802.3u

Standard

s Standard MII management interface and

protocol

s Status Change Interrupt output pin for fast

response time to changed conditions

s 44-pin PLCC CMOS device

s 5 V supply with 3.3 V system interface

compatibility

GENERAL DESCRIPTION

The Am79C989 Quad Ethernet Switching Transceiver

(QuEST™) is a four-port physical layer (PHY) device

that provides all of the analog functions needed for a

10BASE-T switch, including four independent

Manchester Encode/Decode units (MENDECs) and

four independent 10BASE-T transceivers. If the AUI

port is used for a 10BASE-2, 10BASE-5, or

10BASE-FL transceiver, one of the four 10BASE-T

ports is disabled.

The QuEST device is designed for 10 Mbps Ethernet

switching hubs, port switching repeater hubs, routers,

bridges, and servers that require data encoding and

clock recovery on a per port basis and are limited by pin

constraints. Clock recovery is performed as part of the

MENDEC function. The QuEST device supports every

physical layer function of a full-featured switch, includ-

ing full-duplex operation with Auto-Negotiation and the

ability to use various media types.

A unique feature of the QuEST device is the Quad AMD

Switching Interface (QuASI) which multiplexes the data

for all four channels into one set of pins. This minimizes

the pin count and size of the QuEST device and sub-

stantially reduces overall system cost.

The QuEST device provides a 2-pin Media Indepen-

dent Interface (MII) Management Interface which sup-

ports the protocols specified in the IEEE 802.3u

standard. Controlled by the switch system, this inter-

face allows the QuEST device to be polled for status in-

formation and allows operating parameters of the

QuEST device, such as extended distance operation,

to be altered.

The Am79C989 device provides an Interrupt pin to in-

dicate changes in the internal status of the device. The

interrupt function reduces CPU polling of status regis-

ters and allows fast response time to changes in phys-

ical layer conditions.