LAN83C185_03 SMSC [SMSC Corporation], LAN83C185_03 Datasheet - Page 19

• Manufacturer Part Number: LAN83C185_03
• Description: High Performance Single Chip Low Power 10/100 Ethernet Physical Layer Transceiver
• Manufacturer: SMSC [SMSC Corporation]

High Performance Single Chip Low Power 10/100 Ethernet Physical Layer Transceiver (PHY)
Datasheet
Chapter 4 Architecture Details
SMSC LAN83C185
4.1
4.2
4.2.1
4.2.2
Functionally, the PHY can be divided into the following sections:
■
■
■
■
■
The data path of the 100Base-TX is shown in
100M Transmit Data across the MII
The MAC controller drives the transmit data onto the TXD bus and asserts TX_EN to indicate valid
data. The data is latched by the PHY’s MII block on the rising edge of TX_CLK. The data is in the
form of 4-bit wide 25MHz data.
4B/5B Encoding
The transmit data passes from the MII block to the 4B/5B encoder. This block encodes the data from
4-bit nibbles to 5-bit symbols (known as “code-groups”) according to
is mapped to 16 of the 32 possible code-groups. The remaining 16 code-groups are either used for
control information or are not valid.
The first 16 code-groups are referred to by the hexadecimal values of their corresponding data nibbles,
0 through F. The remaining code-groups are given letter designations with slashes on either side. For
example, an IDLE code-group is /I/, a transmit error code-group is /H/, etc.
Top Level Functional Architecture
100Base-TX Transmit
MAC
100Base-TX transmit and receive
10Base-T transmit and receive
MII interface to the controller
Auto-negotiation to automatically determine the best speed and duplex possible
Management Control to read status registers and write control registers
Converter
NRZI
RJ45
MII 25 MHz by 4 bits
TX_CLK
(for MII)
NRZI
MLT-3
Figure 4.1
Converter
MLT-3
100M
PLL
CAT-5
DATASHEET
100Base-TX Data Path
125 Mbps Serial
MII
MLT-3
MLT-3
11
Figure
by 4 bits
Driver
25MHz
Tx
4.1. Each major block is explained below.
Encoder
4B/5B
MLT-3
Magnetics
25MHz by
Table
5 bits
4.1. Each 4-bit data-nibble
Scrambler
and PISO
Rev. 0.6 (12-12-03)