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TUSB320EVM: CC detection when TUSB320 is not powered on

Conor
Guru 10090 points
Part Number: TUSB320EVM
Other Parts Discussed in Thread: TUSB320

Hi,

We are considering replacing USB2.0OTG with Type-C. Verification is performed using TUSB320EVM.

I have doubts whether the TUSB320 on the DRP side is operating normally even though it is not powered on.
I would like to know why CC can be detected even when the TUSB320 is not powered on.

Thanks,

  • 0
    TI__Mastermind 22185 points

    Hi Conor,

    The TUSB320 can operate as a UFP when it is left unpowered.

    This is called "Dead battery mode", and a good description of this mode can be found in the datasheet:

    If you want DRP functionality, you need to power the TUSB320. Otherwise it will default to dead-battery mode, which is UFP only.

    Let me know if you have any questions.

    Best,

    Shane

  • 0 in reply to Shane Hauser
    Guru 10090 points

    Hi Shane,

    Thank you for your reply.
    As far as I can see from your capture, it is connected with 5.1-kΩ±20%Rd, so it can be read that VBUS is supplied regardless of the state of the PORT terminal. Is my understanding correct?

    Thanks,

  • 0 in reply to Conor
    TI__Mastermind 22185 points

    Hi Conor,

    I believe you're correct, let me clarify the behavior:

    The TUSB320 will present as a UFP regardless of the PORT pin setting when in dead battery mode. This means an attached DFP will supply VBUS to the 320 regardless of PORT.

    Best,

    Shane