LAN8720A Ver la hoja de datos (PDF) - SMSC -> Microchip
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LAN8720A Datasheet PDF : 79 Pages
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Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
Chapter 3 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
3.1.1
Transceiver
100BASE-TX Transmit
The 100BASE-TX transmit data path is shown in Figure 3.1. Each major block is explained in the
following subsections.
MAC
Ext Ref_CLK
RMII 50Mhz by 2 bits
RMII
PLL
25MHz 4B/5B 25MHz by Scrambler
by 4 bits Encoder 5 bits and PISO
125 Mbps Serial
NRZI
Converter
NRZI
MLT-3
Converter MLT-3
Tx
Driver
MLT-3 Magnetics MLT-3
RJ45
MLT-3
CAT-5
3.1.1.1
Figure 3.1 100BASE-TX Transmit Data Path
100BASE-TX Transmit Data Across the RMII Interface
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.
SMSC LAN8720A/LAN8720Ai
17
DATASHEET
Revision 1.4 (08-23-12)
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