VT6103 datasheet(22/46 Pages) VIA

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VT6103 - Fast Ethernet 10 / 100 PHY / Transceiver

Revision 1.1 April 15, 2002

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Functional Description

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FUNCTIONAL DESCRIPTION

General

The VT6103 is a complete 10 / 100 Mbps Ethernet Media

Interface IC. The VT6103 has the following main sections:

controller interface, encoder, decoder, scrambler, descrambler,

clock and data recovery, twisted pair transmitter, twisted pair

receiver, and MI serial port. A block diagram is shown in

Figure 3.

The VT6103 can operate as a 100Base-TX device (hereafter

referred to as 100 Mbps mode) or as a 10Base-T device

(hereafter referred to as 10 Mbps mode).

The differences

between 100 Mbps mode and 10 Mbps mode are data rate,

signalling protocol, and allowed wiring. 100 Mbps TX mode

uses two pairs of category 5 or better UTP or STP twisted pair

cable with 4B5B encoded, scrambled, and MLT-3 coded 62.5

MHz ternary data to achieve a throughput of 100 Mbps. 10

Mbps mode uses two pairs of category 3 or better UTP or STP

twisted pair cable with Manchester encoded, 10 MHz binary

data to achieve a 10 Mbps thruput. The data symbol format

on the twisted pair cable for the 100 and 10 Mbps modes is

defined in the IEEE 802.3 specification.

On the transmit side for 100 Mbps TX operation, data is

received on the controller interface from an external Ethernet

controller.

The data is then sent to the 4B5B encoder for

formatting. The encoded data is then sent to the scrambler.

The scrambled and encoded data is then sent to the TP

transmitter.

The TP transmitter converts the encoded and

scrambled data into MLT-3 ternary format, preshapes the

output, and drives the twisted pair cable.

On the receive side for 100 Mbps TX operation, the twisted

pair receiver receives incoming encoded and scrambled MLT-

3 data from the twisted pair cable, removes any high

frequency noise, equalizes the input signal to compensate for

the effects of the cable, qualifies the data with a squelch

algorithm, and converts the data from MLT-3 coded twisted

pair levels to internal digital levels. The output of the twisted

pair receiver then goes to a clock and data recovery block

which recovers a clock from the incoming data, uses the clock

to latch in valid data into the device, and converts the data

back to NRZ format. The NRZ data is then unscrambled and

decoded by the 4B5B decoder and descrambler, respectively,

and outputted to an external Ethernet controller by the

controller interface.

10 Mbps operation is similar to 100

Mbps

operation

except

(1)

there

scrambler/descrambler, (2) the encoder/decoder is Manchester

instead of 4B5B, (3) the data rate is 10 Mbps instead of 100

Mbps, and (4) the twisted pair symbol data is two level

Manchester instead of ternary MLT-3.

The Management Interface, (hereafter referred to as the MI

serial port), is a two-pin bidirectional link through which

configuration inputs can be set and status outputs can be read.

Each block plus the operating modes is described in more

detail in the following sections.

Since the VT6103 can

operate as either a 100Base-TX or a 10Base-T device, each of

the following sections describes the performance of the

respective section in both 100 and 10 Mbps modes.

VT6103 Datasheet(PDF) 22 Page - VIA Technologies, Inc.

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