Design Guide
49
Platform Clock Routing Guidelines
4.1.6
USBCLK Clock Group
For the USBCLK clock group, the driver is the clock synthesizer USB clock output buffer, and the
receiver is the USB clock input buffer at the ICH3-S. Note that this clock is asynchronous to any
other clock on the board.
Figure 4-14. Topology for USB_CLK
Table 4-9. USBCLK Routing Guidelines
Parameter
Routing Guideline
Clock Group
USBCLK
Topology
Point-to-Point
Reference Plane
Ground referenced (contiguous over entire length)
Characteristic Trace Impedance (Z
0
)
50
Ω
± 10%
Trace Width
5 mils
Trace Spacing
25 mils
Trace Length – L1
0.00” – 0.50”
Trace Length – L2
3.00” – 12.00”
Resistor
R1 = 33
Ω
± 5%
Skew Requirements
None – USBCLK is asynchronous to any other clock on the board
Maximum Via Count
2
R1
L1
L2
Intel
®
ICH3-S
Clock
Driver
Summary of Contents for Xeon
Page 24: ...Introduction 24 Design Guide This page is intentionally left blank ...
Page 30: ...Component Quadrant Layout 30 Design Guide This page is intentionally left blank ...
Page 52: ...Platform Clock Routing Guidelines 52 Design Guide This page is intentionally left blank ...
Page 66: ...System Bus Routing Guidelines 66 Design Guide This page is intentionally left blank ...
Page 118: ...Intel 82870P2 P64H2 118 Design Guide This page is intentionally left blank ...
Page 146: ...I O Controller Hub 146 Design Guide This page is intentionally left blank ...
Page 148: ...Debug Port 148 Design Guide This page is intentionally left blank ...
Page 210: ...Schematic Checklist 210 Design Guide This page is intentionally left blank ...
Page 220: ...Layout Checklist 220 Design Guide This page is intentionally left blank ...
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