USB-C Roles: Power, Video and Data

Power Roles

In USB-C world the power roles are referred to as Power Sink and Power Source. In DisplayPort and HDMI terminology sink and source also refer to DUT’s role as sourcing (transmitter) and sinking (receiver) video. In USB-C the video and power role are separate from each other and one device can work simultaneously e.g. as video sink and power source.

The photo below illustrates the different power delivery scenarios within USB-C products. Some products such as a charge can only act as a power source. Some products, like a laptop, can act as both a power source and a power sink. UCD Console enables the swapping of power roles between and it can be swapped separately from the data and video roles.

Application example: a smartphone is a video transmitter that can be charged. In the screenshot below you can see a Samsung S21 smartphone connected to UCD-340. You can see that the Phone is acting as a data master (DFP) but as a power sink.

Click here to learn more about USB-C power delivery.

DisplayPort Alternate Mode

DisplayPort video sink and source roles are referred to as DFP_D (Source) and UFP_D (Sink). DP Alt Mode roles cannot be assigned before the PD negotiation.

USB data

Initially the USB data role is defined by the power role i.e. power source becomes the DFP and power sink becomes the UFP. Unlike the power role, the data role cannot be swapped once DP Alt mode contract has been established.

USB-C Products

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