Intel Pentium 4 Processor in the 478-pin Package / Intel 850 Chipset Platform Family Design Guide

Platform Clock Routing Guidelines
R
Intel
®
Pentium
®
4 Processor / Intel
®
850 Chipset Family Platform Design Guide 57
4.4.2 66 MHz Clock Routing Length Guidelines
Table 8. 66 MHz Clock Routing Length Guidelines
Clock Group Length of Trace A (in) Length of Trace B (in) R1 (Ω)
AGP_66 0” to 0.5” Z 33
CLK_66 0” to 0.5” Z + (4” – 5”) 33
NOTE: The routing length value of Z is 5 to 9 inches.
Figure 28 and Figure 29 show the recommended clock routing topologies for the 66 MHz clocks.
Figure 28. AGP_66 Clock Routing Topology
AGP Connector
R1
A
CK00
Clock
Synthesizer
B
Clk_Routing_AGP-66
Figure 29. CLK_66 Clock Routing Topology
R1
A
CK00
Clock
Synthesizer
MCH
R1
ICH2
AB
B
Clk_Routing_CLK-66
4.4.2.1 3V66 Clock Routing Requirement for Intel
®
82850E Platforms
The 3V66 trace (CK_G_66M_MCH) from the Clock Chip to MCH cannot be shorter than the
CPU Clock trace (CK_H_100M_MCH, CK_H_100M_MCH).