82575 Ethernet Controller Design Guide

Even with a perfect support circuit, most crystals will oscillate slightly higher or slightly lower than the exact center of the target frequency. Therefore, frequency measurements (which determine the correct value for C1 and C2) should be performed with an ideal reference crystal. When the capacitive load is exactly equal to the crystal’s load rating, an ideal reference crystal will be perfectly centered at the desired target frequency.

5.11.1Reference Crystal Selection

There are several methods available for choosing the appropriate reference crystal:

•If a Saunders and Associates (S&A) crystal network analyzer is available, then discrete crystal components can be tested until one is found with zero or nearly zero ppm deviation (with the appropriate capacitive load). A crystal with zero or near zero ppm deviation will be a good reference crystal to use in subsequent frequency tests to determine the best values for C1 and C2.

•If a crystal analyzer is not available, then the selection of a reference crystal can be done by measuring a statistically valid sample population of crystals, which has units from multiple lots and approved vendors. The crystal, which has an oscillation frequency closest to the center of the distribution, should be the reference crystal used during testing to determine the best values for C1 and C2.

•It may also be possible to ask the approved crystal vendors or manufacturers to provide a reference crystal with zero or nearly zero deviation from the specified frequency when it has the specified CLoad capacitance.

When choosing a crystal, customers must keep in mind that to comply with IEEE specifications for 10/100 and 10/100/1000Base-T Ethernet LAN, the transmitter reference frequency must be precise within ±50 ppm. Intel® recommends customers to use a transmitter reference frequency that is accurate to within ±30 ppm to account for variations in crystal accuracy due to crystal manufacturing tolerance..

5.11.2Circuit Board

Since the dielectric layers of the circuit board are allowed some reasonable variation in thickness, the stray capacitance from the printed board (to the crystal circuit) will also vary. If the thickness tolerance for the outer layers of dielectric are controlled within ±17 percent of nominal, then the circuit board should not cause more than ±2 pF variation to the stray capacitance at the crystal. When tuning crystal frequency, it is recommended that at least three circuit boards are tested for frequency. These boards should be from different production lots of bare circuit boards.

Alternatively, a larger sample population of circuit boards can be used. A larger population will increase the probability of obtaining the full range of possible variations in dielectric thickness and the full range of variation in stray capacitance.

Next, the exact same crystal and discrete load capacitors (C1 and C2) must be soldered onto each board, and the LAN reference frequency should be measured on each circuit board.

The circuit board, which has a LAN reference frequency closest to the center of the frequency distribution, should be used while performing the frequency measurements to select the appropriate value for C1 and C2.

5.11.3Temperature Changes

Temperature changes can cause the crystal frequency to shift. Therefore, frequency measurements should be done in the final system chassis across the system’s rated operating temperature range.

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Intel 317698-001 manual Reference Crystal Selection, Circuit Board, Temperature Changes
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317698-001 specifications

The Intel 317698-001 is a prominent and highly regarded component in the realm of computer hardware. This product is part of Intel's extensive portfolio, designed primarily for enhancing computing performance, efficiency, and reliability. It is typically associated with server motherboards and is known for its robust architecture, making it ideal for enterprise-level applications.

One of the standout features of the Intel 317698-001 is its compatibility with multiple Intel processors, which provides flexibility for users looking to upgrade or configure their systems. This compatibility ensures that enterprises can choose from a range of processors according to their specific workload requirements, allowing for tailored performance enhancements.

The product is built on the foundation of advanced technologies, such as Intel's Turbo Boost and Hyper-Threading. Turbo Boost allows the processor to operate at higher frequencies than its base clock speed when demand increases, providing a significant performance boost when needed. Hyper-Threading enables multiple threads to run simultaneously on each core, which can lead to improved multitasking capabilities and more efficient resource utilization.

Memory bandwidth is another vital characteristic of the Intel 317698-001. This component supports high-speed DDR4 memory, offering increased bandwidth that is crucial for data-intensive applications. The architecture is designed to work seamlessly with ECC (Error-Correcting Code) memory, enhancing system reliability by detecting and correcting internal data corruption.

In terms of connectivity, the Intel 317698-001 features multiple PCIe lanes, supporting various expansion cards for enhanced functionality. This includes the integration of NVMe drives for faster storage solutions, which is essential for modern applications that demand quick data access and retrieval.

Security is also a priority with the Intel 317698-001, which incorporates hardware-based security features to protect data integrity and prevent unauthorized access. These features include Intel Trusted Execution Technology, which creates a secure environment for executing sensitive code.

Overall, the Intel 317698-001 stands out with its combination of performance, versatility, and security. It is an ideal choice for businesses looking to enhance their computing capabilities while ensuring system reliability and security in an increasingly data-driven world. With its robust technological foundation, it continues to play a critical role in modern computing environments.
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