Intel Pentium 4

Platform Clock Routing Guidelines
R
58 Intel
®
Pentium
®
4 Processor / Intel
®
850 Chipset Family Platform Design Guide
4.4.3 33 MHz Clock Routing Length Guidelines
Table 9 summarizes the layout recommendations between the CK00 clock synthesizer and PCI
connectors, ICH2, FWH and SIO components that require a 33 MHz clock.
Table 9. 33 MHz Clock Routing Guidelines
Clock Group Length of Trace A
(inches)
Length of Trace B
(inches)
R1 (Ω)
PCI_33 0 to 0.5 Z + (2 – 4) 33
CLK_33 0 to 0.5 Z + (4 – 6) 33
NOTE: The routing length value of Z is 5 to 9 inches.
Figure 30 and Figure 31 show the recommended clock routing topologies for the 33 MHz clocks.
Figure 30. PCI_33 Clock Routing Topology
CK00 Clock
Synthesizer
P
C
I
S
L
O
T
P
C
I
S
L
O
T
P
C
I
S
L
O
T
P
C
I
S
L
O
T
P
C
I
S
L
O
T
R1
R1
R1
R1
R1
A
A
A
A
A
B
B
B
B
B
Clk_Routing_PCI-33