5220-DS02-R datasheet(13/90 Pages) BOARDCOM

13 / 90 page

Preliminary Data Sheet

BCM5220

04/20/04

Broa d c om Co rp o r a t i o n

Document

5220-DS04-405-R

Overview

Page 1

Secti on 1: Fu nction al Descri p ti on

OVERVIEW

The BCM5220 is a single-chip Fast Ethernet transceiver. It performs all of the physical layer interface functions for 100BASE-

TX full-or half-duplex Ethernet on CAT 5 twisted pair cable and 10BASE-T full-or half-duplex Ethernet on CAT 3, 4 or 5 cable.

It may also be configured for 100BASE-FX full-or half-duplex transmission over fiber-optic cabling when paired with an

external fiber-optic line driver and receiver.

The chip performs 4B5B, MLT3, NRZI, and Manchester encoding and decoding, clock and data recovery, stream cipher

scrambling/descrambling, digital adaptive equalization, line transmission, carrier sense and link integrity monitor, auto-

negotiation and Media Independent Interface (MII) management functions. The BCM5220 can be connected to a MAC

switch controller through the MII on one side, and connects directly to the network media on the other side (through isolation

transformers for unshielded twisted pair (UTP) modes or fiber-optic transmitter/receiver components for FX modes). The

BCM5220 is fully compliant with the IEEE 802.3 and 802.3u standards.

ENCODER/DECODER

In 100BASE-TX and 100BASE-FX modes, the BCM5220 transmits and receives a continuous data stream on twisted-pair

or fiber-optic cable. When the MII transmit enable is asserted, nibble-wide (4-bit) data from the transmit data pins is encoded

into 5-bit code groups and inserted into the transmit data stream. The 4B5B encoding is shown in Table 1 on page 5. The

transmit packet is encapsulated by replacing the first 2 nibbles of preamble with a start of stream delimiter (J/K codes) and

appending an end of stream delimiter (T/R codes) to the end of the packet. When the MII transmit error input is asserted

during a packet, the transmit error code group (H) is sent in place of the corresponding data code group. The transmitter

repeatedly sends the idle code group between packets.

In TX mode, the encoded data stream is scrambled by a stream cipher block and then serialized and encoded into MLT3

signal levels. A multi-mode transmit DAC is used to drive the MLT3 data onto the twisted pair cable. In FX mode, the

scrambling function is bypassed and the data is NRZI encoded. The multimode transmit DAC drives differential positive ECL

(PECL) levels to an external fiber-optic transmitter.

Following baseline wander correction, adaptive equalization, and clock recovery in TX mode, the receive data stream is

converted from MLT3 to serial NRZ data. The NRZ data is descrambled by the stream cipher block and then deserialized

and aligned into 5-bit code groups.

In FX mode, the receive data stream differential PECL levels are sampled from the fiber-optic receiver. Baseline wander

correction, adaptive equalization, and stream cipher descrambling functions are bypassed and NRZI decoding is used

instead of MLT3.

The 5-bit code groups are decoded into 4-bit data nibbles, as shown in Table 1. The start of stream delimiter is replaced with

preamble nibbles and the end of stream delimiter and idle codes are replaced with all zeros. The decoded data is driven onto

the MII receive data pins. When an invalid code group is detected in the data stream, the BCM5220 asserts the MII RXER

signal. The chip also asserts RXER for several other error conditions that improperly terminate the data stream. While RXER

is asserted, the receive data pins are driven with a 4-bit code indicating the type of error detected. The error codes are listed

in Table 2 on page 6.

5220-DS02-R 数据表(PDF) 13 Page - Broadcom Corporation.

5220-DS02-R 数据表(HTML) 13 Page - Broadcom Corporation.

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