82562EZ(EX)/82547GI(EI) Dual Footprint Design Guide
3.0
Ethernet Component Design Guidelines
These sections provide recommendations for selecting components and connecting special pins.
The main design elements are the 82562EZ(EX) Platform LAN Connect device or the
82547GI(EI) Gigabit Ethernet Controller, an integrated 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 or 10/100/1000 Mb/s.
Follow good engineering practices with respect to unused inputs by terminating them with pull-up
or pull-down resistors, unless the data sheet, design guide or reference schematic indicates
otherwise. Do not attach pull-up or pull-down resistors to any balls identified as No Connect.
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.
lists the crystal electrical parameters and provides suggested values for typical designs. The
parameters listed are described in the following subsections.
Table 5.
Crystal Parameters
Parameter
Vibration Mode
Nominal Frequency
Frequency Tolerance
Fundamental
25,000 MHz at 25
°
C (required)
• ±30 ppm recommended; ±50 ppm across the entire operating
temperature range as required by IEEE specifications
• ±30 ppm required for the 82547GI(EI)
Temperature Stability
Calibration Mode
Load Capacitance
Shunt Capacitance
Equivalent Series Resistance
Drive Level
Aging
• ±50 ppm at 0
°
C to 70
°
C
• ±30 ppm at 0
°
C to 70
°
C required for the 82547GI(EI)
Parallel
• 16 pF to 20 pF
• 18 pF required for the 82547GI(EI)
6 pF maximum
• 50
Ω
maximum
• 10
Ω
maximum required for the 82547GI(EI)
0.5 mW maximum
±5 ppm per year maximum
Suggested Value
7
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