January 2007 217
Intel
®
855GME Chipset and Intel
®
6300ESB ICH Embedded Platform Design Guide
Intel
®
6300ESB Design Guidelines
Placing the capacitance near the USB connectors for cables that share power and ground
conductors is required to ensure the system passes droop requirements. Cables that provide
individual power and ground conductors for each port may usually meet droop requirements by
providing adequate capacitance near the motherboard mating connector, since droop is actually an
effect felt by adjacent ports due to switching transients on the aggressor port. In the separate
conductor case, all transients will be seen/dampened by the capacitance at the motherboard mating
connector before they may cause problems with the adjacent port sharing the same cable. See
sections 7.2.2 and 7.2.4.1 of the
Universal Serial Bus Specification, Revision 2.0, for more details.
Note: Cables that contain more than two signal pairs are not recommended due to unpredictable
impedance characteristics.
9.6.6.2 Motherboard/PCB Mating Connector
Proper selection of a motherboard mating connector for front panel USB support is important to
ensure signal quality is not adversely affected due to a poor connector interface. The cable and
PCB mating connector must also pass the TDR requirements listed in the
Universal Serial Bus
Specification, Revision 2.0
.
9.6.6.2.1 Pin-Out
A ten pin, 0.1-inch pitch stake pin assembly is recommended with the pin-out listed in
Table 9.6.6.3 and schematic shown in Figure 112.
Table 87. Front Panel Header Pin-Out
Pin Description
1Vcc
2Vcc
3dm1
4dm2
5dp1
6dp2
7GND
8GND
9key
10 no connect or over-current sense
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