I/O Apic (I/O Advanced Programmable Interrupt Controller); Figure 63. Recommended Usb Schematic - Intel 815 Design Manual

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Figure 63. Recommended USB Schematic

P+
P-
ICH
The recommended USB trace characteristics are as follows:
Impedance 'Z0' = 45.4
Line delay = 160.2 ps
Capacitance = 3.5 pF
Inductance = 7.3 nH
Res at 20 C = 53.9 m
10.5 I/O APIC (I/O Advanced Programmable Interrupt
Controller)
Systems not using the I/O APIC should comply with the following recommendations:
On the ICH
Connect PICCLK directly to ground.
Connect PICD0, PICD1 to ground through a 10 k resistor.
On the processor
PICCLK requires special implementation for universal motherboard designs. See Section
4.2.9
Connect PICD0 to 2.5V through 10 k resistors.
Connect PICD1 to 2.5V through 10 k resistors.
®
Intel 815 Chipset Platform Design Guide
Driver
15
< 1"
47 pF
15 k
Driver
15
< 1"
47 pF
15 k
Transmission line
Motherboard trace
45
Motherboard trace
45
I/O Subsystem
90
USB twisted-pair cable
USB_schem
123