WJLXT972ALC.A4 S E001 Intel, WJLXT972ALC.A4 S E001 Datasheet - Page 30

• Manufacturer Part Number: WJLXT972ALC.A4 S E001
• Manufacturer: Intel

Specifications of WJLXT972ALC.A4 S E001

• Lead Free Status / Rohs Status: Compliant

Intel
5.3
5.3.1
5.3.2
5.3.2.1
5.3.2.2
30
®
LXT972A Single-Port 10/100 Mbps PHY Transceiver
Note:
Note:
Operating Requirements
Power Requirements
The LXT972A Transceiver requires three power supply inputs:
The digital and analog circuits require 3.3 V supplies (VCCA and VCCD). These inputs may be
supplied from a single source. Each supply input must be de-coupled to ground.
An additional supply may be used for the MII (VCCIO). The supply may be either +2.5 V or
+3.3 V. Also, the inputs on the MII interface are tolerant to 5 V signals from the controller on the
other side of the MII interface. For MII I/O characteristics, see
Characteristics1 - MII Pins” on page
Bring up power supplies as close to the same time as possible.
As a matter of good practice, keep power supplies as clean as possible.
Clock Requirements
External Crystal/Oscillator
The LXT972A Transceiver requires a reference clock input that is used to generate transmit signals
and recover receive signals. It may be provided by either of two methods: by connecting a crystal
across the oscillator pins (XI and XO) with load capacitors, or by connecting an external clock
source to pin XI.
The connection of a clock source to the XI pin requires the XO pin to be left open. To minimize
transmit jitter, Intel recommends a crystal-based clock instead of a derived clock (that is, a PLL-
based clock).
A crystal is typically used in NIC applications. An external 25 MHz clock source, rather than a
crystal, is frequently used in switch applications. For clock timing requirements, see
Characteristics - REFCLK/XI and XO Pins” on page
MDIO Clock
The MII management channel (MDIO) also requires an external clock. The managed data clock
(MDC) speed is a maximum of 8 MHz. For details, see
MDIO Timing” on page
•
•
•
VCCA
VCCD
VCCIO
75.
64.
65.
Table 37, “Intel® LXT972A Transceiver
Table 23, “Digital I/O
Document Number: 249186-004
Revision Date: 25-Oct-2005
Table 24, “I/O
Datasheet