Datasheet

LAN8710A/LAN8710AI
DS00002164B-page 16  2016 Microchip Technology Inc.
3.0 FUNCTIONAL DESCRIPTION
This chapter provides functional descriptions of the various device features. These features have been categorized into
the following sections:
• Transceiver
• Auto-negotiation
• HP Auto-MDIX Support
• MAC Interface
• Serial Management Interface (SMI)
• Interrupt Management
• Configuration Straps
• Miscellaneous Functions
• Application Diagrams
3.1 Transceiver
3.1.1 100BASE-TX TRANSMIT
The 100BASE-TX transmit data path is shown in Figure 3-1. Each major block is explained in the following subsections.
FIGURE 3-1: 100BASE-TX TRANSMIT DATA PATH
MAC
Tx
Driver
MLT-3
Converter
NRZI
Converter
4B/5B
Encoder
CAT-5RJ45
25MHz by
5 bits
NRZI
MLT-3MLT-3
MLT-3
Scrambler
and PISO
MII/RMII
25MHz
by 4 bits
Ext Ref_CLK (for RMII only)
PLL
MII 25 Mhz by 4 bits
or
RMII 50Mhz by 2 bits
MLT-3
Magnetics
125 Mbps Serial
TX_CLK
(for MII only)
3.1.1.1 100BASE-TX Transmit Data Across the MII/RMII Interface
For MII, the MAC controller drives the transmit data onto the TXD bus and asserts TXEN to indicate valid data. The data
is latched by the transceiver’s MII block on the rising edge of TXCLK. The data is in the form of 4-bit wide 25MHz data.
For RMII, the MAC controller drives the
transmit data onto the TXD bus and asserts TXEN to indicate valid data. The
data is latched by the transceiver’s RMII block on the rising edge of REF_CLK. The data is in the form of 2-bit wide
50MHz data.
3.1.1.2 4B/5B Encoding
The transmit data passes from the MII/RMII 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 Table 3-1. Each 4-bit data-nibble is mapped to 16 of the 32 pos-
sible code-groups. The remaining 16 code-groups are either
used for control information or are not valid.