USB Voltage at the ADSF-BF53x USB

Document created by analog-archivist Employee on Feb 23, 2016
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My ADSP-BF52x USB based product is unpowered, however, when I plug in a USB
cable from the computer I measure some voltage on VDDUSB.  Is this normal?  Is
there a path from USB_VBUS to other power domains on the processor?


It is normal to see voltage on VDDUSB, there's a path from USB_VBUS to VDDUSB
on BF52x and BF60x processors.  This is done order to power the circuitry that
protects the USB controller against exposure to 5V from VBUS while the
processor is unpowered.  In fact, you should always see some voltage on VDDUSB
when VBUS is present.