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.

DISTINCTIVE CHARACTERISTICS
■ Four independent 10BASE-T transceivers compliant with the IEEE 802.3 standard
■ Four digital Manchester Encode/Decode (MENDEC) units
■ On-chip filtering enables FCC EMI compliance without external filters or common mode chokes
■ Automatic polarity Correction and Detection on 10BASE-T receivers
■ Optional Attachment Unit Interface (AUI) for non-10BASE-T transceivers
■ 10BASE-T Extended Distance option accommodate lines longer than 100 meters
■ Quad AMD Switching Interface (QuASI™) interface reduces overall pin count
■ Half-Duplex and Full-Duplex operation
■ Auto-Negotiation compliant with IEEE 802.3u Standard
■ Standard MII management interface and protocol
■ Status Change Interrupt output pin for fast response time to changed conditions
■ 44-pin PLCC CMOS device
■ 5 V supply with 3.3 V system interface compatibility