lan9311 Standard Microsystems Corp., lan9311 Datasheet - Page 84

• Manufacturer Part Number: lan9311
• Description: Lan9311/lan9311i Two Port 10/100 Managed Ethernet Switch With 16-bit Non-pci Cpu Interface
• Manufacturer: Standard Microsystems Corp.

Revision 1.2 (04-08-08)
7.2.1
7.2.1.1
7.2.1.2
Port x
MAC
Converter
NRZI
100BASE-TX Transmit
The 100BASE-TX transmit data path is shown in
internal to the PHY. Each major block is explained in the following sections.
MII MAC Interface
For a transmission, the switch fabric MAC drives the transmit data to the PHYs MII MAC Interface.
The MII MAC Interface is described in detail in
Note: The PHY is connected to the switch fabric MAC via standard MII signals. Refer to the IEEE
4B/5B Encoder
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.
RJ45
MII 25 MHz by 4 bits
MII Transmit Clock
802.3 specification for additional details.
NRZI
Internal
Internal
MLT-3
Converter
MLT-3
Figure 7.2 100BASE-TX Transmit Data Path
MII MAC
Interface
CAT-5
100M
PLL
MLT-3
DATASHEET
125 Mbps Serial
MLT-3
by 4 bits
84
25MHz
Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface
TX Driver
100M
Section 7.2.7, "MII MAC
Figure
Encoder
4B/5B
7.2. Shaded blocks are those which are
MLT-3
Table
25MHz by
Magnetics
5 bits
Interface".
7.2. Each 4-bit data-nibble
SMSC LAN9311/LAN9311i
Scrambler
and PISO
Datasheet