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

I/O Controller Hub 2
R
Intel
®
Pentium
®
4 Processor / Intel
®
850 Chipset Family Platform Design Guide 149
Figure 104 illustrates the recommended USB schematic:
Figure 104. USB Data Signals
15k
15k
15 ohm
15 ohm
ICH2
P+
P-
USB Connector
< 1"
< 1"
90 ohm
45 ohm
45 ohm
Driver
Driver
USB Twisted Pair CableTransmission Line
Motherboard Trace
Motherboard Trace
Optional 47 pf
Optional 47 pf
The following are Recommended USB Trace Characteristics.
• Impedance ‘Z0’ = 45.4 Ω
• Line Delay = 160.2 ps
• Capacitance = 3.5 pF
• Inductance = 7.3 nH
• Res @ 20° C = 53.9 m Ω
9.5 IOAPIC Design Recommendations
The IOAPIC bus is not required in these designs.
• Processor:
 The processor does not have these pins defined. It receives interrupts for servicing via the
System Bus interrupt delivery mechanism.
• On the ICH2
 Tie PICCLK directly to ground
 Tie PICD0, PICD1 to ground via 1 k Ω to 10 kΩ resistor