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General Description

The DM8108 is an 8 port 10/100Mbit/s nonblocking Ethernet switch with on-chip address-lookup engine. The DM8108 provides a low-cost, high-performance switch solution with PHYs and single SGRAM.

Features

■ Low cost Fast Ethernet Switching Controller.

• Provide packet switching functions between eight 10/100Mbps, auto-negotiated on-chip Fast Ethernet ports and a proprietary Full-duplex Expansion port.

• Cascade max. 8 DM8108s without extra glue logic for 64-port configuration.

■ Incorporates three 802.3 compliant 10/100Mbps Media Access Controllers

• Direct interface to MII (Media Independent Interface)

• Half/Full Duplex Support for individual port (upto 200Mbps/port)

• IEEE 802.3 100Base-TX, T4.FX compatible

■ Auto-negotiation supported through Serial MII interface

■ High-performance Distributed Switching Engine

• Performs packet forwarding and filtering at full wire-speed

• 148,800 packets/sec. on each Ethernet port

■ Direct support for packet buffering

• Glue-less interface with 1 or 2 Mbytes of SDRAM (SGRAM)

• 32 bit memory bus configuration

• 66 Mhz – 90Mhz memory bus speed

• Up-to 1.1K buffers, 1536-byte each, allocated to receive ports

■ Support Store and Forward switching approach

• Low last-bit to first-bit out delay

• Allow mixed speed Ethernet packet switching

• Allow conversion between different protocols

■ Flow control

• Support partitioning function

• Support back-pressure while lack of internal resources

• Support 802.3x PAUSE function in full duplex mode

• Support up to 4-port trunking for 800Mbps bandwidth

■ Advanced Address Learning and Searching

• Self learning mechanism

• Cache 128 address entries internally

• Record up-to 16K Uni-cast MAC addresses and unlimited Multicast and Broadcast addresses

• Automatic aging scheme

• Broadcast filtering rate control

■ Expansion Bus

• Up-to 8 SW devices can be cascaded via expansion bus without extra logic

• Full duplex mode transfer

• Less Bus overhead

• Automatic flow control

■ Complete status report to a simple LED interface

■ Suitable for low cost Switch market to replace Hub

■ 0.35
m process, 3.3V with 5V tolerant I/O

■ 208-pin PQFP package