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CC2540 USB self powered mode

Sasha Kalmanovich
Intellectual 840 points
Other Parts Discussed in Thread: CC2540

Is it possible to connect a USB connector in a self powered mode to the CC2540 ?

Are any GPIO pins (except the dedicated USB pins) needed ?

Thanks.

  • 0
    TI__Genius 17975 points

    Could you please explain what you mean by "connect a USB connector in a self powered mode to the CC2540"?

  • 0 in reply to Willis1
    Intellectual 840 points

    The CC2540 has a USB module.

    In the usb dobgle board, the power to the board is supplied from the USB bus - it is called bus powered.

    I want to create a design in which the power to the CC2540 is supplied by another source, and the USB is used only for communication (It is called self powered).

    Thanks,

    Sasha.

  • 0 in reply to Sasha Kalmanovich
    Intellectual 535 points

    This is an interesting question, I would love to have an answer to this too. Also how much current is drained trough the DVDD_USB pin? I have to option to power  DVDD_USB from VBUS, but then I need a 5 to 3V converter which will add cost. If I power it directly from the battery, it will obviously add a load to the battery therefore shorten it's life. Also in self powered mode do I need to monitor the VBUS? I think the USB specification requires this, but I'm not sure.

    If I power  DVDD_USB from VBUS, what happens if my battery is empty (VBUS is higher than VDD)? Could this in any way damage the chip? Is there a safe operating area, say battery goes down to 2V and VBUS is still 3.3V?

     

    Thanks

     

    Reto