Specifications

Intel
®
810E2 Chipset Platform
R
Design Guide
167
7.2.8. USB
Checklist Items Recommendations
USBP[3:0]P
USBP[3:0]N
See Figure 92 for circuitry needed on each differential Pair.
VCC USB (Cable
power)
It should be powered from the 5V core instead of the 5V standby, unless adequate standby
power is available.
Voltage drop
considerations
The resistive component of the fuses, ferrite beads and traces must be considered when
choosing components, and power and GND trace widths. Minimize the resistance between
the Vcc5 power supply and the USB ports to prevent voltage drop.
Sufficient bypass capacitance should be located near the USB receptacles to minimize the
voltage drop that occurs during the hot plugging a new device. For more information, see the
USB specification.
Fuse A fuse larger than 1A can be chosen to minimize the voltage drop.
Figure 92. USB Data Line Schematic
15 k Ω
15 k Ω
15 Ω
15 Ω
ICH2
P+
P-
< 1"
< 1"
45 Ω
45 Ω
Driver
Driver
Transmission line
Motherboard trace
Motherboard trace
usb_data_line_schem
USB connector
90 Ω
USB twisted-pair cable
Optional
47 pf
Optional
47 pf