P4080 USB Specific FAQs

Document created by Omar Cruz Employee on Aug 6, 2012
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If I don’t use the USB interface in the 4080, can I leave USBx_VDD_3P3 and USBx_VDD_1P0 pins not connected? In P4040 they are reserve with note do not connect. Can they be connected to 3.3V and 1.0V respectively?

USB_VDD_1P0 must be tied to 1V or the platform voltage (based on whatever the SOC core digital power supply is). USB_VDD_3P3 can be left floating.

If I don’t use USB, is it safe to leave USBx_IBIAS_REXT and USBx_VDD_1P8_DECAP unconnected?

If USB is not to be used at all, keep the following USB signals floating : USB1_IBIAS_REXT, USB2_IBIAS_REXT, USB1_VDD_1P8_DECAP and USB2_VDD_1P8_DECAP, USB1_VDD_3P3, USB2_VDD_3P3.