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
FIGURE 3-9: SOURCING REF_CLK FROM EXTERNAL 25MHZ SOURCE
LAN8720A/LAN8720Ai
10/100 PHY
24-QFN
RMII
TXP
TXN
Mag RJ45
RXP
RXN
XTAL1/CLKIN
XTAL2
TXD[1:0]
2
RXD[1:0]
CRS_DV
2
RMII
LED[2:1]
2
Interface
MDIO
MDC
nRST
TXEN
REFCLKO
MAC
Capable of
accepting 50MHz
clock
Note: nINT is not available in
this configuration
RXER
25MHz
Clock
REF_CLK
2016 Microchip Technology Inc. DS00002165B-page 31
LAN8720A/LAN8720AI
3.8 Miscellaneous Functions
3.8.1 LEDS
Two LED signals are provided as a convenient means to determine the transceiver's mode of operation. All LED signals
are either active high or active low as described in Section 3.8.1.2, "nINTSEL and LED2 Polarity Selection" and Section
3.8.1.1, "REGOFF and LED1 Pola
rity Selection," on page 33.
The LED1 output is driven active whenever the device detects a va
lid link, and blinks when CRS is active (high) indicat-
ing activity.
The LED2 output is driven active when the
operating speed is 100Mbps. This LED will go inactive when the operating
speed is 10Mbps or during line isolation.
Note: Wh
en pulling the LED1 and LED2 pins high, they must be tied to VDD2A, NOT VDDIO.