TUSB321AI: Will power role change during VDD in?

Hi Kailun,

Kailun Liu said:

When VDD_5V is not present, VDD is without power. And a tablet is connected to type C (supporting OTG), the pad provides VBUS power internally. If VDD is powered on again at this time (the port pin is pulled up, indicating it is a DFP), will the TUSB321 adjust the role to provide charging to the pad? 

The TUSB321AI will need to be reset in order to adjust the role. Power-up will not reset the negotiation.

Kailun Liu said:

When the TUSB321A operates as a UFP, does it negotiate current capability? How is the current negotiated, and what is the maximum it can support?

When configured as a UFP, the TUSB321A will detect what the advertised current of the DFP is via the voltage of the CC pins. Then, the TUSB321A will communicate what the detected current is via the OUT1 and OUT2 pins of the device, with the status of the pins indicating whether it detects the default current(900ma), 1.5A, or 3A.

3A is the max advertisable/detectable current. A PD controller allows for higher current.

Thanks,

Ryan