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TPS65987D: Power direction and USB communication direction

daniel
Genius 5095 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TUSB320,

Hi Team,

Does DFP/UFP/DRP means Power direction or USB communication direction?

As I know USB2.0 D+/D- has host and device distinguish, and the communication direction is from host to device.

Could a product play a role as power source and USB2.0 host simultaneously?

If yes, does it called "power role swap" which only supported by PD controller? So CC analog like TUSB320 can't support it?

Thanks

  • 0
    TI__Mastermind 30000 points
    Hello Daniel,

    Typically, DFP/UFP/DRP is used to describe the data role, and Source/Sink describe the power role.

    Yes a product can play as a power source and USB2.0 host. Think of an example where your have a Type-C to legacy dongle, with a legacy USB thumb drive attached. The Type-C device would act as the source to power the cable and thumb drive, while also acting as the host to retrieve data from the drive.

    A power role swap only occurs with Type-C PD devices, and are typically done by a PD controller. But for the example with the C to legacy dongle, a power role swap is not needed.

    Hope this helps answer your question.
  • 0 in reply to Adam Mc Gaffin
    Genius 5095 points

    Hi Adam,

    Many thanks for your reply.

    Sorry for my typo. I want to ask:

    Could a product play a role as power source and USB2.0 device simultaneously?

    Or, Could a product play a role as power sink and USB2.0 device simultaneously?

    If yes, does it called "power role swap"?

    My product is a docking with Type-C connector, use TPS65987D as 5V/9V/12V/15V/20V power source.

    If my product connect to a legacy host to a type-C sink cable, which have a pullup resistor internally.

    In that condition, No TPS65987D source PDO would negotiated successfully, since both side cc pins are pullup, right?

    So in that condition, can USB communicate still workable? Or power active/non-active would not affect data communication?

    Or should I need to add a Sink PDO 5V even if my produce just as 5V/9V/12V/15V/20V power source?

    Thanks

  • 0 in reply to daniel
    TI__Mastermind 30000 points
    Hello,

    Yes, there could be an instant where product is a power source and USB device, but this is not related to power role swap. A power role swap is when a device starts out in one power role (source/sink), but decides to change to the other based (source/sink). An example of this would be a Type-C charging port on a Laptop. Traditionally, you want your laptop to be able to power and charge any device that is connected to it (memory sticks, phones, keyboard, etc...) so the laptop will start out as a source. However, when you connect a dedicated type-c charger or a dock to the type-C port on the laptop, you want the laptop to begin charging. This is done through power role swap. The laptop would first advertise as a Source/DFP, and the advertise a power role swap to a Sink/DFP once it detects its been connected to a dedicated charger.

    USB communication should not be contingent on cc pins as long as a contract is negotiated between the two devices