Intel 82547EI, Design Manual

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82562EZ(EX)/82547GI(EI) Dual Footprint Design Guide
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Figure 12. Direct Probing Method
A.6 Direct Frequency Measurement and Frequency Accuracy
Calculation Steps
1. Make sure the system BIOS has the LAN controller enabled.
2. Connect the test equipment as shown in Figure 12 .
3. Using the appropriate controls for your model of high resolution digital counter, make sure it
can display ~25.0000 MHz with at least four decimal places frequency resolution.
4. Ensure the LAN circuits are powered.
5. Determine the center reference frequency as accurately as possible. This can be done by taking
30 to 50 different readings using the frequency counter and then calculating the average results
of the readings.
6. Calculate the accuracy of the measured and averaged center frequency with respect to an ideal
25.0000 MHz reference frequency.