LAN8742AI-CZ datasheet(4/124 Pages) MICROCHIP

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LAN8742A/LAN8742Ai

DS00001989A-page 4

 2013-2015 Microchip Technology Inc.

1.0

INTRODUCTION

1.1

General Terms and Conventions

The following is a list of the general terms used throughout this document:

1.2

General Description

The LAN8742A/LAN8742Ai 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 and 802.3u standards.

The LAN8742A/LAN8742Ai supports communication with an Ethernet MAC via a standard RMII interface. It contains a

full-duplex 10-BASE-T/100BASE-TX transceiver and supports 10 Mbps (10BASE-T) and 100 Mbps (100BASE-TX)

operation. The LAN8742A/LAN8742Ai implements 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. Inte-

grated Wake on LAN (WoL) support provides a mechanism to trigger an interrupt upon reception of a perfect DA, broad-

cast, magic packet, or wakeup frame.

The LAN8742A/LAN8742Ai supports 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". Register-selectable configuration options may be used to further define

the functionality of the transceiver.

The LAN8742A/LAN8742Ai can be programmed to support wake-on-LAN at the physical layer, allowing detection of

configurable Wake-up Frame and Magic packets. This feature allows filtering of packets at the PHY layer, without requir-

ing MAC intervention. Additionally, the LAN8742A/LAN8742Ai supports cable diagnostics which allow the device to

identify opens/shorts and their location on the cable via vendor-specific registers.

Per IEEE 802.3-2005 standards, all digital interface pins are tolerant to 3.6 V. The device can be configured to operate

on a single 3.3 V supply utilizing an integrated 3.3 V to 1.2 V linear regulator. The linear regulator may be optionally

disabled, allowing usage of a high efficiency external regulator for lower system power dissipation.

The LAN8742A/LAN8742Ai is available in commercial (0°C to +70°C) and industrial (-40°C to +85°C) temperature

range versions. A typical system application is shown in Figure 1-1. Figure 1-2 provides an internal block diagram of the

device.

BYTE

8 bits

FIFO

First In First Out buffer; often used for elasticity buffer

MAC

Media Access Controller

RMII™

Reduced Media Independent Interface

N/A

Not Applicable

Indicates that a logic state is “don’t care” or undefined.

RESERVED Refers to a reserved bit field or address. Unless otherwise noted, reserved bits must always be zero

for write operations. Unless otherwise noted, values are not guaranteed when reading reserved bits.

Unless otherwise noted, do not read or write to reserved addresses.

SMI

Serial Management Interface

FIGURE 1-1:

SYSTEM BLOCK DIAGRAM

LAN8742A/

LAN8742Ai

10/100

Ethernet

MAC

RMII

Mode

LED

Transformer

Crystal or

Clock

Oscillator

MDI

RJ45

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