Mobile Intel Pentium 4 Processor - M and Intel 845MP/MZ Chipset Platform Design Guide

Mobile Intel
®
Pentium
®
4 Processor-M and Intel
®
845MP/845MZ Chipset Platform
152 Design Guide
R
Figure 82. Topology for CLK66
A
R1
Clock
Driver
MCH and
ICH2
B
Table 51. CLK66 Routing Guidelines
Parameter Routing Guidelines
Clock Group CLK66
Topology Point to point
Reference Plane Ground Referenced (Contiguous over entire Length)
Characteristic Trace Impedance (Zo) 55 Ohms ± 15%
Trace Width 4 mils
Trace Spacing 20 mils
Spacing to other traces 20 mils
Trace Length – A 0.00” to 0.50”
Trace Length – B 4.00” to 8.50”
Resistor R1 = 33 Ohms +/- 1%
Skew Requirements All the clocks in the CLK66 group should have minimal skew (~ 0)
between each other with tolerance of 500 pS
Clock Driver to MCH-M X
Clock Driver to ICH X ± 100 mils
If the trace length from the clock driver to the MCH-M is X, the trace length from clock to ICH must be
X ± 100 mils.
10.3.3. AGPCLK Clock Group
The driver is the clock synthesizer 66-MHz clock output buffer and the receiver is the 66-MHz clock
input buffer at the AGP device. Note that the goal is to have minimal (~ 0) skew between this clock and
the clocks in the clock group CLK66.