RU82566DC INTEL [Intel Corporation], RU82566DC Datasheet - Page 22

• Manufacturer Part Number: RU82566DC
• Description: 82566 Gigabit Platform LAN Connect
• Manufacturer: INTEL [Intel Corporation]

82566 Gigabit Platform LAN Connect Networking Silicon Datasheet
18
Table 21. Crystal Specifications (Sheet 2 of 2)
Figure 4. Crystal Connectivity to the 82566
Note: Refer to Technical Advisory (TA-181), the 82566 Board Layout Checklist, and the 82566 Design
a. When not using values within 1% of the recommended values, the following procedures must be used:
b. Differential board capacitance is the capacitance between Ser_CLK_PLUS and Ser_CLK_MINUS.
c. Board capacitance is the differential capacitance between the input and output. This parasitic capacitance must be less than
Checklist for details relating to
1. On the board with the crystal and the 82566, measure the clock at the output of the receive and transmit lines.
2. Change C
3. Ensure the demand on the 25 MHz clock has a deviation of less then 100 ppm (for example, 25 ± 0.0025 MHz).
4. If the measured frequency is higher then 25.0025 MHz, replace capacitors C
5. If the measured frequency is lower then 24.9975 MHz, replace capacitors C
or equal to the specification. This value can change up to 10%. The procedures listed in footnote “a” must be followed to com-
ply with the ppm specification.
External Capacitors
Board Capacitance
Parameter Name
Board Resistance
Differential Board
Capacitance
1
Crystal Pad
and C
2
to meet with the 25 MHz requirement.
Symbol
C
1
C
C
R
Figure
, C
Resistor
D
s
s
30-ohm
Capacitor
0402
2
27pF
0402
“C”
“B”
4.
Ethernet Controller
Recommended Value
Less than 660 mils
Xtal2
Crystal
“A”
27 pF
0.1 Ω
2 pF
4 pF
Xtal1
“B”
Capacitor
27pF
0402
1
1
and C
and C
Max/Min Range
2
2
with smaller capacitors.
with larger capacitors.
1 Ω
b
c
a
Crystal Pad
Conditions
-
-
-