3X38FTR Datasheet, PDF(33/64 Page) Agere Systems – OCTAL-FET (Fast Ethernet Transceiver) for 10Base-T/100Base-TX/FX

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

3X38FTR Datasheet, PDF (33/64 Pages) Agere Systems – OCTAL-FET (Fast Ethernet Transceiver) for 10Base-T/100Base-TX/FX

◁

Preliminary Data Sheet

September 2000

3X38FTR 208-Pin SQFP

OCTAL-FET for 10Base-T/100Base-TX/FX

Functional Description (continued)

100Base-X Transmitter

The 100Base-X transmitter consists of functional blocks

which convert synchronous 4-bit nibble data, as pro-

vided by the internal MII, to a 125 Mbits/s serial data

stream. This data stream may be routed either to the

on-chip twisted-pair PMD for 100Base-TX signaling, or

to an external fiber-optic PMD for 100Base-FX applica-

tions. The 3X38 implements the 100Base-X transmit

state machine as specified in the IEEE 802.3U Stan-

dard, Clause 24 and comprises the following functional

blocks in its data path:

s Symbol encoder

s Scrambler block

s Parallel/serial converter and NRZ/NRZI encoder

block

Symbol Encoder

The symbol encoder converts 4-bit (4B) nibble data

generated by the RMII-MII module into 5-bit (5B) sym-

bols for transmission. This conversion is required to

allow control symbols to be combined with data sym-

bols. Refer to the table below for 4B to 5B symbol map-

ping.

Following onset of the TXEN signal, the 4B/5B symbol

encoder replaces the first two nibbles of the preamble

from the MAC frame with a /J/K code-group pair

(11000 10001) start-of-stream delimiter (SSD). The

symbol encoder then replaces subsequent 4B codes

with corresponding 5B symbols. Following negation of

the TXEN signal, the encoder substitutes the first two

IDLE symbols with a /T/R code-group pair (01101

00111) end-of-stream delimiter (ESD) and then contin-

uously injects IDLE symbols into the transmit data

stream until the next transmit packet is detected.

Table 11. Symbol Code Scrambler

Symbol

Name

5B Code

[4:0]

11110

01001

10100

10101

01010

01011

01110

01111

10010

10011

10110

10111

11010

11011

11100

11101

11111

11000

10001

01101

00111

00100

00000

00001

00010

00011

00101

4B Code

[3:0]

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

1011

1100

1101

1110

1111

Undefined

0101

Undefined

Interpretation

Data 0

Data 1

Data 2

Data 3

Data 4

Data 5

Data 6

Data 7

Data 8

Data 9

Data A

Data B

Data C

Data D

Data E

Data F

IDLE: interstream fill code

First start-of-stream delimiter

Second start-of-stream delimiter

First end-of-stream delimiter

Second end-of-stream delimiter

Halt: transfer error

Invalid code

Lucent Technologies Inc.

▷