USB Type-C is a specification for the USB connector system, increasingly popular in smartphones and mobile devices, capable of both power delivery and data transmission. USB-C is a relatively new standard, with the current version being USB4, which uses dual-lane links to achieve transmission bandwidths of up to 40Gbps and power up to 240W. These features make USB-C a truly universal connection standard for modern devices. Signal diagram of USB Type-C main functions introduction: The USB Type-C connector has 24 pins. Figures 1 and 2 show the pinouts of the USB Type-C receptacle and plug, respectively. PCB design and routing requirements for USB Type-C: Power delivery and alternate modes of USB Type-C: Devices using the USB Type-C standard can negotiate and select appropriate power levels through the interface. These power negotiations are implemented through a protocol called USB Power Delivery, which is a single-wire communication on the CC line mentioned above. The figure below shows an example of USB power delivery, where the sink sends requests to the source and adjusts the VBUS voltage as needed. First, a 9V bus is requested. After the source stabilizes the bus voltage at 9V, it sends a "Power Ready" message to the sink. Then, the sink requests a 5V bus, and the source provides it and sends the "Power Ready" message again. It is worth noting that "USB Power Delivery" involves not only power-related negotiations; other negotiations, such as those related to alternate modes, are also conducted using the power delivery protocol on the standard CC line.