TUSB320EVM: CC detection when TUSB320 is not powered on

Conor

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,

over 2 years ago

0 Shane Hauser over 2 years ago

TI__Mastermind 34605 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 Conor over 2 years ago in reply to Shane Hauser

Guru 14110 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 Shane Hauser over 2 years ago in reply to Conor

TI__Mastermind 34605 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

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TUSB320EVM: CC detection when TUSB320 is not powered on