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Can the USB0_VBUS pin be unconnected when the USB device operation?

RY9983
Guru 10570 points

Hello.

I am using USB as device only mode operation.
I have pulled up USB0_VBUS pin to 5V with an external 1K ohm resistor.
I would not like it(USB0_VBUS) to connect to VBUS of USB connector for ESD.

Is this allowed ?(Does USB operate correctly?)

Best regards,
RY

  • 0
    TI__Genius 14545 points

    RY,

    RY said:
    Is this allowed ?(Does USB operate correctly?)

        To clarify your question, you would like to know if USB_VBUS can be tied to a external 5V supply (not that of the USB) during normal operation?

    If so, then yes according to the USB spec, a device can be 'self powered' from an external source and does not need to draw current from the USB_VBUS. You can find the details USB device specifications in Chapter 9 of the USB spec available from the USB Website.

    The operation of the bus is largely dependent on the programming of the USB Device driver - but from an electrical point of view, it should be ok to power from an external 5V to isolate from the USB_VBUS source.

     

     

     

     

  • 0 in reply to dabuan
    Guru 10570 points

    Hello Drew.
    Thank you very much for your answer !

    Best regards,
    RY