Source Clock Topology To Down Devices (Except Pci-E); 100 Mhz Src/Src# Clock Routing Guidelines For Down Devices(Except Pci-E) - Intel EP80579 Manual

8.2.2.3 Source Clock to Down Devices
Figure 55.

Source Clock Topology to Down Devices (Except PCI-E)

C lock D river
C K410
Table 19.

100 MHz SRC/SRC# Clock Routing Guidelines for Down Devices(Except PCI-E)

Trace Width (W)
Differential Pair Spacing (S)
Spacing to Other Traces (S1)
Motherboard Impedance – Differential
Routing Length (L1, L1'):
Clock Driver to Rs
Routing Length (L2, L2'):
Rs to Rs-Rt Node
Routing Length (L3, L3'):
Rs-Rt Node to Rt
Routing Length (L4, L4'):
Rs-Rt Node to Load
SRC to SRC# Length Matching
Resistors
Notes:
1. Routing guidelines are for the width is 4.5 mils with 10 mil spacing on layers 3 & 8. Use 4.5-mil line
width and adjust the trace to trace air gap to achieve 100 Ω differential impedance.
2. Trace width and differential spacing is stackup dependent.
3. Clock traces are routed in a differential configuration. Maintain the minimum recommended spacing
between the two traces of the pair. Maintain uniform spacing along the entire length of the trace. Do
not exceed the maximum trace spacing, as this will degrade the noise rejection of the network.
4. The differential impedance of each clock pair is the critical parameter. Single-ended impedance may
vary with different geometries.
5. Minimize L1, L2 and L3 lengths. Long lengths on L2 and L3 degrade effectiveness of source
termination and contribute to ringback.
®
Intel EP80579 Integrated Processor Product Line
Platform Design Guide
97
®
Intel EP80579 Integrated Processor Product Line—Platform System Clock
LT = L1 + L2 + L4
R s
L1
L1'
R s
Layout Guideline
L2 L4
L2' L4'
L3
L3'
R t R t
Value
microstrip: 4.5 mils
stripline: 4.75 mils
10 mils
20 mils
Ω ±
100 10%
0.5in. max
0.2in. max
0.2in. max
Min: 1in.
Max: 16in.
within 5 mils
Ω
Rs = 22-33 ±5%
Ω Ω
Rt = 49.9 ±1% (for 100
differential impedance)
SATA, or other
dow n devices
(Except PC I-E)
Figure Notes
Figure 57 1,2
Figure 57 3,4
Figure 57
3,4
Figure 55 5
Figure 55 5
Figure 55 5
Figure 55
Figure 55
May 2010
Order Number: 320068-005US