AM79C984AJC

LAN HUB CONTROLLER, 84Pin, PLCC

GENERAL DESCRIPTION

The enhanced Integrated Multiport Repeater eIMR device is a VLSI integrated circuit that provides a system-level solution to designing non-managed multiport repeaters. The device integrates the repeater functions specified in Section 9 of the IEEE 802.3 standard and Twisted Pair Transceiver functions complying with the 10BASE-T standard.

DISTINCTIVE CHARACTERISTICS

■ Repeater functions comply with IEEE 802.3 Repeater Unit specifications

■ Four integral 10BASE-T transceivers with on chip filtering that eliminate the need for external filter modules on the 10BASE-T transmit-data TXD and receive-data RXD lines

■ One Reversible Attachment Unit Interface RAUI™ port that can be used either as a standard IEEE-compliant AUI port for connection to a Medium Attachment Unit MAU, or as a reversed port for direct connection to a Media Access Controller MAC

■ Low cost suitable for non-managed multiport repeater designs

■ Expandable to increase number of repeater ports with support for up to seven eIMR devices without the need for an external arbiter

■ All ports can be individually isolated partitioned in response to excessive collision conditions or fault conditions.

■ Full LED support for individual port status LEDs and network utilization LEDs

■ Programmable extended distance mode on the RXD lines, allowing connection to cables longer than 100 meters

■ Twisted Pair Link Test capability conforming to the 10BASE-T standard. The Link Test function and the transmission of Link Test pulses can be optionally disabled through the control port to allow devices that do not implement the Link Test function to work with the eIMR device.

■ Programmable option of automatic polarity detection and correction permits automatic recovery due to wiring errors

■ Full amplitude and timing regeneration for retransmitted waveforms

■ CMOS device with a single +5-V supply