EVB-USB3280 User Manual
SMSC EVB-USB3280
Revision 2.0 (12-18-06)
3
1.5
VBUS Present Detection
The SIE must detect VBUS when the USB cable is attached. The EVB-USB3280 ships with a resistive
voltage divider (R19 & R20) to divide the 5V signal to 3.3V at the T&MT connector. The resistor values
may be changed to meet the voltage requirements of the SIE.
The values used in this resistive divider will determine how much VBUS current is consumed during
suspend. A device must properly report this value in the descriptors.
1.6
UTMI Signal Test Points
The headers J2 through J6 provide convenient access to the UTMI signals, and each pin is labeled
with a signal name as shown in
Figure 2
.
1.7
T&MT Connector Pinout
The T&MT specification defines the pin assignments for the T&MT connector. A link to the T&MT
specification is located in the SPECIFICATIONS section of the USB3280 web page on the SMSC
website. Please refer to the EVB-USB3280 schematic for information regarding which signals are used
and how the signals are connected in this implementation. site.
1.8
Board Schematic
The schematic diagram is included for reference, and can be enlarged for increased readablity. The
schematic is also available from the SMSC web site as a separate pdf document.
Figure 2 UTMI Signal Test Points
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