SLYY228 November 2024
Implementing USB 3.0 data rates on a 5V USB-C source-only port introduces the need for an additional system block, a USB 3.0 multiplexer. USB 3.0 uses the SSTX and SSRX pins of the USB-C connector. In order to route the correct pins to the USB 3.0 physical layer (PHY) within the system, a multiplexer controlled by a CC controller handles the bidirectional flip of the USB-C connector. CC controllers will have a general-purpose input/output (GPIO) for indicating the CC polarity. This GPIO output from the CC controller connects to the multiplexer polarity control input.
In addition to requiring a multiplexer, a USB-C port supporting USB 3.0 data is also required to support VCONN, since USB 3.0 cables typically include an e-marker or active redriver, which are powered by VCONN. Note that VCONN is provided on the unused CC pin. Although it is possible to implement VCONN discretely through another load switch or power path, the simplest way to add VCONN capabilities is to use a CC controller with an integrated VCONN power path, as illustrated in Figure 45.
Figure 45 5V source with USB3 mux block
diagramWhen supporting USB 3.0 data in any direction, the requirements for supporting VCONN and including a USB 3.0 multiplexer remain. The type of USB 3.0 multiplexer will vary, depending on whether you need an upward-facing port or downward-facing port. However, the GPIO interface between the CC controller and the USB 3.0 multiplexer remain the same (single GPIO to indicate polarity). Because these hierarchical requirements are identical, the remaining sections on 5V USB-C source-only ports without USB PD will focus on the differences in power architectures.