USB-C

The USB-C cable serves as an important bridge for power input (charging) and device reception (phone/computer/tablet) to communicate and participate in power transmission. The connector board can incorporate an 'E-Marker' as a communication medium to participate in 'information negotiation,' which is responsible for informing both ends (device side and power supply side) of the acceptable and deliverable current and voltage.

Note that the E-Marker is 'optional,' and not all TYPE-C cables will have this chip. According to the USB Implementers Forum (USB-IF) regulations, charging cables with currents exceeding 3A must embed an E-marker chip in the Type-C charging cable head to ensure the safety of its use. However, cables without the E-Marker chip limit the current to 3A for safety reasons, preventing potential safety issues from high resistance and high current overheating. Cables with a 3A E-Marker chip maintain a maximum current transmission of 3A for the entire fast charging system. With a 5A E-Marker chip, the maximum current transmission of the entire fast charging system can reach 5A. The maximum power transmission specifications of USB-C data cables are mainly divided into two types: 60W/100W/240W, categorized by current as 3A cables/5A cables. Apart from Thunderbolt data cables, the power transmission performance of other data cables is not directly related to their data transmission performance.

Thunderbolt™ is a high-speed I/O interface developed by Intel in 2009, primarily intended for use as a transmission cable between computers and other devices, with the aim of replacing and unifying the various interfaces found on computers. Intel introduced the first generation of Thunderbolt™ in 2011, integrating the interface with Mini DisplayPort, with a transmission speed of up to 10Gbps, and supporting daisy-chain connection of up to six peripheral devices.

　　In 2013, Thunderbolt™ 2 was introduced, doubling its transmission speed to 20Gbps, with the interface remaining the same as the first generation, still using Mini DisplayPort. In 2015, Thunderbolt™ 3 was released, once again doubling the transmission speed to 40Gbps. In addition to this, Thunderbolt™ made a significant change in this generation by adopting the USB Type-C interface, supporting a maximum power delivery of 100W, and enabling support for two 4K displays or one 5K display. Thanks to the decision to integrate with USB Type-C, Thunderbolt™ 3 has become more popular than Thunderbolt™ and Thunderbolt™ 2.

　　As for Thunderbolt™ 4, released in 2020, it also uses the USB Type-C interface. While the maximum transmission speed remains at 40Gbps, the PCIe bandwidth has been upgraded from 16Gbps in Thunderbolt™ 3 to 32Gbps in Thunderbolt™ 4. This means that Thunderbolt™ 4 offers significant improvements in transmission speed and performance for PCIe devices such as storage devices and external graphics cards. The charging power remains at 100W (increased to 240W after PD3.1).

From appearance, both USB4 and Thunderbolt™ 4 use the USB Type-C interface. They both support a maximum transmission speed of 40Gbps, as well as video output and power delivery of up to 240W. Therefore, it's easy to confuse the two. So what are the differences between USB4 and Thunderbolt™ 4? The answer is: The most obvious difference lies in the 'minimum specification requirements'.

．Bandwidth Support　Although both support a maximum bandwidth of 40Gbps, USB4 has two specifications: USB4 20Gbps and USB4 40Gbps, so the minimum requirement is only 20Gbps, while Thunderbolt™ 4 only has one specification, which is 40Gbps.

．Data Transfer Speed　As for data transfer, USB4 requires a minimum support of USB 3.2 at 10Gbps, while Thunderbolt™ 4 can achieve 10Gbps through USB 3.2 or up to 32Gbps via PCIe.

．Dispaly Support　In terms of display support, USB4 supports one display without a minimum resolution requirement, while Thunderbolt™ 4 must be able to support two 4K 60Hz monitors or one 8K 30Hz monitor.