Kontron COMe Starterkit Eval T2 - Manual (Page 85)

COM Express Interfaces
ESD protection diodes D7 through D12 provide overvoltage protection caused by ESD and
electrical fast transients . Low capacitance diodes and transient voltage suppression diodes
should be placed near the USB connector. The example design uses an Ultra-Low capacitance
ESD diode array from Infineon. (http://www.infineon.com).
The example designs show a 0 Ohm resistor connecting Chassis Ground and Logic Ground at
the USB connector. Many USB devices connect Chassis and Logic grounds together. To
minimize the current in this path a ferrite, resistor or capacitor connecting Chassis Ground to
Logic Ground should be placed close to the USB connector.
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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