Intel
®
EP80579 Integrated Processor Product Line May 2010
Order Number: 320068-005US 173
Universal Serial Bus (USB) Interface—Intel
®
EP80579 Integrated Processor Product Line
12.7 Front Panel Solutions
12.7.1 Internal USB Cables
The front panel internal cable solution must meet all the requirements of Chapter 6 in
the USB 2.0 Specification for high/full-speed cabling for each port with the exceptions
described in Section 12.7.1.2, “Internal Cable Option 2” on page 173.
12.7.1.1 Internal Cable Option 1
Use standard high/full-speed compatible USB cables.
These must meet all cabling requirements called out in Chapter 6 of the USB 2.0
Specification. The recommended motherboard mating connector pin-out is covered in
Section 12.7.2, “Motherboard/PCB Mating Connector” on page 174.
12.7.1.2 Internal Cable Option 2
Use custom cables that meet all of the requirements of Chapter 6 in the USB 2.0
Specification with the following additions/exceptions:
• The cables can share a common jacket, shield, and drain wire.
• Two ports with signal pairs that share a common jacket may combine Vbus and
ground wires into a single wire, provided the following conditions are met:
— The bypass capacitance required by Section 7.2.4.1 of the USB 2.0
Specification is physically located near the power and ground pins of the USB
connectors. This is easiest to achieve by mounting the front panel USB
connectors and the bypass capacitance on a small PCB (daughter card). See
Section 12.7.3, “Front Panel Daughter Card” on page 176 for details.
— Selecting the proper wire size. A general rule for replacing two power or ground
wires with a single wire is to choose a wire size from Table 6-6 in Section 6.6.3
of the USB 2.0 Specification that has equal or less than half the resistance of
either of the two wires being combined. The data is provided for reference in
Table 65.
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