TPS25751: Regarding the TI's PD controller

Hello Kyohei,

Thank you for your response.

I help support the USB Controller Product Line at TI. I am able to answer your questions regarding PD controllers, and then I will reassign this thread to the TUSB320 team to answer your questions in regard to the TUSB320.

Kyohei said:

Is there a PD controller available that supports the above configuration?

The TPS25751 supports both power role and data role swaps. 

Kyohei said:

Is this still the case when operating in DRP (Dual Role Port) mode?

For theTPS25751, it utilizes the CC lines to detect a connection to port and the cable orientation. A PD controller has a pullup resistor to VBUS, and a pulldown resistor to GND connected to the CC pins. The CCx toggles high and low till a cable is detected. A CCx will be pulled up or down depending on the orientation of the connection. This is the typical behavior for this device when it is operating as a DRP, a sink, or a source.

Kyohei said:

I believe host-device recognition is typically determined at the time of USB connection.
If a PD controller IC is used, is it possible to change roles even after USB startup? (by writing to the above register etc..)

A PD controller, such as the TPS25751, can send 4CC commands to the systems MCU in order to request a power role or data role swap. 

Thank you,

Katilynn

Hi Kyohei,

Kyohei said:

I understand that the basic role is determined by connecting external PD/PU resistors to the CC lines on the board.
Is this still the case when operating in DRP (Dual Role Port) mode?

Yes, this is still the case. The TUSB320 will toggle the CC lines high and low using the pull-up and pull-downs inside the controller, and will set it's role depending on how the connection seen over the CC lines.

Kyohei said:

Referring to the TUSB320, it seems that writing to the MODE_SELECT register at address 0x0A allows switching to DRP mode.
Does this mean that the DRP state can be forcibly set regardless of the resistor values on the CC pins?

Yes, I2C can be used to set the device role, however this change will only take effect when there is no connection over the CC lines. If there is a connection, this role swap will not take place. For changing roles while there is a connection, a PD controller would need to be used.

Thanks,

Ryan