Datasheet
Table Of Contents
- Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
- 1.0 Introduction
- 2.0 Pin Description and Configuration
- 3.0 Functional Description
- 3.1 Transceiver
- 3.2 Auto-negotiation
- 3.3 HP Auto-MDIX Support
- 3.4 MAC Interface
- 3.5 Serial Management Interface (SMI)
- 3.6 Interrupt Management
- 3.7 Configuration Straps
- 3.8 Miscellaneous Functions
- 3.9 Application Diagrams
- 4.0 Register Descriptions
- 4.1 Register Nomenclature
- 4.2 Control and Status Registers
- TABLE 4-2: SMI Register Map
- 4.2.1 Basic Control Register
- 4.2.2 Basic Status Register
- 4.2.3 PHY Identifier 1 Register
- 4.2.4 PHY Identifier 2 Register
- 4.2.5 Auto Negotiation Advertisement Register
- 4.2.6 Auto Negotiation Link Partner Ability Register
- 4.2.7 Auto Negotiation Expansion Register
- 4.2.8 Mode Control/Status Register
- 4.2.9 Special Modes Register
- 4.2.10 Symbol Error Counter Register
- 4.2.11 Special Control/Status Indications Register
- 4.2.12 Interrupt Source Flag Register
- 4.2.13 Interrupt Mask Register
- 4.2.14 PHY Special Control/Status Register
- 5.0 Operational Characteristics
- 6.0 Package Information
- 7.0 Application Notes
- Appendix A: Data Sheet Revision History
- The Microchip Web Site
- Customer Change Notification Service
- Customer Support
- Product Identification System
- Worldwide Sales and Service
LAN8720A/LAN8720AI
DS00002165B-page 4 2016 Microchip Technology Inc.
1.0 INTRODUCTION
1.1 General Terms and Conventions
The following is list of the general terms used throughout this document:
BYTE 8-bits
FIFO First In First Out buffer; often used for elasticity buffer
MAC Media Access Controller
RMII™ Reduced Media Independent Interface
TM
N/A Not Applicable
X Indicates that a logic state is “don’t care” or undefined.
RESERVED Refers to a reserved bit field or address. Unless otherwise
no
ted, reserved bits must always be zero for write opera-
tions. Unless otherwise noted, values are not guaranteed
whe
n reading reserved bits. Unless otherwise noted, do
not read or write to reserved addresses.
SMI Serial Management Interface
1.2 General Description
The LAN8720A/LAN8720Ai is a low-power 10BASE-T/100BASE-TX physical layer (PHY) transceiver with variable I/O
voltage that is compliant with the IEEE 802.3-2005 standards.
The LAN8720A/LAN8720Ai supports communication with an Eth
ernet MAC via a standard RMII interface. It contains a
full-duplex 10-BASE-T/100BASE-TX transceiver and supports 10Mbps (10BASE-T) and 100Mbps (100BASE-TX) oper-
ation. The LAN8720A/LAN8720Ai implement
s auto-negotiation to automatically determine the best possible speed and
duplex mode of operation. HP Auto-MDIX support allows the use of direct connect or cross-over LAN cables.
The LAN8720A/LAN8720Ai support
s both IEEE 802.3-2005 compliant and vendor-specific register functions. However,
no register access is required for operation. The initial configuration may be selected via the configuration pins as
described in Section 3.7, "Configuration Straps," on page 29. Register-selectable configuration options may be used to
further define the functionality of the transceiver.
Per IEEE 802.3-2005 standards, all digital interface pins are tole
rant to 3.6V. The device can be configured to operate
on a single 3.3V supply utilizing an integrated 3.3V to 1.2V linear regulator. The linear regulator may be optionally dis-
abled, allowing usage of a high efficiency external regulator for lower system power dissipation.
The LAN8720A/LAN8720Ai is available in both extended comme
rcial and industrial temperature range versions. A typ-
ical system application is shown in Figure 1-1.