Intel 82562EX, Руководство по конструкции

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82540EP/82541(PI/GI/EI) & 82562EZ(EX) Dual Footprint Design Guide
5
3.0 Ethernet Component Design Guidelines
This section provides recommendations for selecting components and connecting special pins. The
main design elements are the 82562EZ(EX) Platform LAN Connect device or the 82540EP/
82541xx Gigabit Ethernet Controller, a magnetics module with RJ-45 connector, and a crystal
clock source.
3.1 General Design Considerations for Ethernet Controllers
These recommendations apply to all designs, 10/100 Mbps or 10/100/1000 Mbps.
Good engineering practices should be followed with respect to unused inputs by terminating them
with pull-up or pull-down resistors, unless the datasheet, design guide or reference schematic
indicates otherwise. Do not attach pull-up or pull-down resistors to any balls identified as
RESERVED (unless explicitly included in the reference schematic). These devices may have
special test modes that could be entered inadvertently.
3.1.1 Crystal Selection Parameters
Quartz crystals are generally considered to be the mainstay of frequency control components due to
their low cost and ease of implementation. They are available from numerous vendors in many
package types and with various specification options.
All crystals used with Intel
®
Ethernet controllers are described as “AT-cut”, which refers to the
angle at which the unit is sliced with respect to the long axis of the quartz stone.
Table 3 lists the crystal electrical parameters and provides suggested values for typical designs. The
parameters listed are described in the following subsections.
Table 3. Crystal Parameters
Parameter Suggested Value
Vibration Mode Fundamental
Nominal Frequency 25,000 MHz at 25
°
C (required)
Frequency Tolerance • ±30 ppm recommended; ±50 ppm across the entire operating
temperature range as required by IEEE specifications
• ±30 ppm required for the 82541EI/GI
Temperature Stability • ±50 ppm at 0
°
C to 70
°
C
• ±30 ppm at 0
°
C to 70
°
C required for the 82541EI/GI
Calibration Mode Parallel
Load Capacitance • 16 pF to 20 pF
• 18 pF required for the 82541EI/GI
Shunt Capacitance 6 pF maximum
Equivalent Series Resistance • 50
Ω
maximum
• 20
Ω
maximum required for the 82541EI/GI
Drive Level 0.5 mW maximum
Aging ±5 ppm per year maximum