Ethernet Component Design Guidelines; General Design Considerations For Ethernet Controllers; Crystal Selection Parameters; Crystal Parameters - Intel 82541PI Design Manual

3.0

Ethernet Component Design Guidelines

This section provides recommendations for selecting components and connecting special pins. The
main design elements are the 82562GZ(GX) PLC device or the 82541PI(ER) Gagabit Ethernet
controller, external resistor connections (82562GZ(GX) only), 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
angle at which the unit is sliced with respect to the long axis of the quartz stone.
Table 5 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
Nominal Frequency
Frequency Tolerance
Temperature Stability
Calibration Mode
Non Operating Temperature
Load Capacitance
Pullability from Nominal Load
Shunt Capacitance
Equivalent Series Resistance
Application Note (AP-468)
82541PI(ER) and 82562GZ(GX) Dual Footprint LOM Design Guide
®
Ethernet controllers are described as "AT-cut", which refers to the
Parameter
Vibration Mode Fundamental
25,000 MHz at 25
• ±30 ppm recommended; ±50 ppm across the entire operating
• ±30 ppm required for the 82562GZ(GX)
• ±50 ppm at 0
• ±30 ppm at 0
Parallel
-40 to 90
Range
• 16 pF to 20 pF
• 20 pF required for the 82562GZ(GX)
15 ppm/pF maximum for the 82562GZ(GX)
Capacitance
6 pF maximum
50 Ω maximum
Suggested Value
°
C (required)
temperature range as required by IEEE specifications
° °
C to 70 C
° °
C to 70 C required for the 82562GZ(GX)
°
C for the 82562GZ(GX)
7