AN983 datasheet(67/91 Pages) ETC

67 / 91 page

AN983B

PCI/miPCI Fast Ethernet Controller with integrated PHY

Start-of-Stream Delimiter-SSD (/J/K/)

In a transmission stream, the first 16 nibbles are MAC preamble. In order to let

partner delineate the boundary of a data transmission sequence and to authenticate

carrier events, the transceiver will replace the first 2 nibbles of the MAC preamble

with /J/K/ code-groups.

End-of-Stream Delimiter-ESD (/T/R/)

In order to indicate the termination of the normal data transmissions, the transceiver

will insert 2 nibbles of /T/R/ code-group after the last nibble of FCS.

Scrambling

All the encoded data (including the idle, SSD, and ESD code-groups) is passed to data

scrambler to reduce the EMI and spread the power spectrum using a 10-bit scrambler

seed loaded at the beginning.

Data conversion of Parallel to Serial, NRZ to NRZI, NRZI to MLT3

After scrambled, the transmission data with 5B type in 25MHz will be converted to

serial bit stream in 125HMz by the parallel to serial function. After serialized, the

transmission serial bit stream will be further converted from NRZ to NRZI format.

After NRZI converted, the NRZI bit stream is passed through MLT3 encoder to generate

the TP-PMD specified MLT3 code. With this MLT3 code, it lowers the frequency and

reduces the energy of the transmission signal in the UTP cable and also makes the

system easily to meet the FCC specification of EMI.

Wave-Shaper and Media Signal Driver

In order to reduce the energy of the harmonic frequency of transmission signals, the

transceiver provides the wave-shaper prior the line driver to smooth but keep

symmetric the rising/falling edge of transmission signals. The wave-shaped signals

include the 100BASE-TX and 10BASE-T both are passed to the same media signal driver.

This design can simplify the external magnetic connection with single one.

100BASE-TX Receiving Operation

Regarding the 100BASE-TX receiving operation, the transceiver provides the receiving

functions of PMD, PMA, and PCS for receiving incoming data signals through category 5

UTP cable and an isolation transformer with turn’s ratio of 1: 1.

It includes the adaptive

equalizer and baseline wander, data conversions of MLT3 to NRZI, NRZI to NRZ and serial

to parallel, the PLL for clock and data recovery, the de-scrambler, and the decoder of 5B/4B.

Adaptive Equalizer and Baseline Wander

Since the high-speed signals over the unshielded (or shielded) twisted Pair cable will

induce the amplitude attenuation and phase shifting. Furthermore, these effects are

depends on the signal frequency, cable type, cable length and the connectors of the

ADMtek Inc.

www.admtek.com.tw

Rev. 1.8

AN983 数据表(PDF) 67 Page - List of Unclassifed Manufacturers

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