The USB type-c interface, also known as the type-c interface or USB c interface, is considered by many brands as the future unified interface due to its ease of use in both forward and reverse insertion and support for high-speed transmission. In the beautiful vision of these brands, after the popularization of USB C, we no longer need to distinguish between headphones, mobile phones, and even the connecting cables of computers and screens. Whether it's transmitting videos, sending files, or providing power, a unified USB C cable can all take care of it. In recent years, the common lightweight laptops that only carry USB C interfaces represent the wild hope of USB C and computer interfaces.

Unfortunately, even the versatile USB C interface actually has its own shortcomings. Taking the power supply with the highest demand as an example: some high-performance laptops may experience a phenomenon of less and less charging even when connected to an external power supply when fully powered on, and many users hope to use USB C to power their gaming computers.

Because at present, the USB C interface can only theoretically supply 120W power in the 5V20A PD format, it is obviously not practical to use USB C to power game laptops. But recently, after the USB IF organization changed the standards for the USB interface, this idea is likely to become a reality.

What is the significance of high power USB C! In version 2.1 of the USB type-c cable and interface standard, the power delivery limit of the USB c interface has been raised to a maximum of 240W, and it has also been named Extended Power Range.

In the current era where USB C can only deliver 100W, Dell and other brands of monitors have integrated the ability to deliver 90W power, which can reverse supply up to 90W power to laptops through a fully functional USB. From a book perspective, it has surpassed the 65W power supply requirements of many lightweight laptops, even the 87W power supply of the MacBook Pro 16 inch version is not a problem.

For the USB C interface, expanding the power supply to 240W online can not only achieve the advanced idea of USB C cables supplying power to gaming laptops, but also provide a significant improvement in the field of computer related power supply. In addition to gaming laptops, smaller universal interfaces can be replaced, and even devices such as screens and graphics card docks can be directly powered through USB C cables.

For example, for a monitor, in addition to the displayed video cable (HDMI/DP), a national standard word power cable is also indispensable. But if USB C can transmit power at higher power, future screens may acquire video signals and power simultaneously from a fully functional USB C connected to a computer, making the screen a front-line device like a mouse. Considering that 240W is sufficient to drive most displays, with the cooperation of daisy chain technology, we are expected to significantly optimize the number of cables for multi screen combinations.

The emergence of high-power USB C interfaces not only integrates existing power lines into data lines, but also enables some devices that are not connected to USB C to use a unified power interface. Imagine that routers, NAS, PS5, and screens all use USB C interfaces, which is obviously a huge benefit for some users: you don't need to prepare any cables, just buy two more fully functional USB Cs.

What are the technical difficulties of high-power USB C? Why did USB-IF only add 240W of standard bricks to the USB specification until now? The reason is simple: at present, USB C, regardless of interface or cable, cannot afford 240W of power.

First, look at the USB C interface pins. You may not know that there are 12 contacts on each side of the substrate in the USB C interface, with a total of 24 points on the front and back sides. But apart from the ground wire, diagnosis, and signals, only four contacts are truly used for power supply. In other words, the 240W power is only shared by four small contacts, which poses a great challenge to the security of the USB C interface.

In addition, USB C is only one aspect of power transmission. Whether it is the voltage transformation stage before or after power transmission, it is a significant challenge for the adapter. Another issue is the thickness of the wire, as for most USB C cables, there is no possibility of transmitting 240W power.

Why don't I think this is a good thing, but then again, even if USB-IF finds a way to transmit 240W power using USB C in the future, I don't think it's a good idea. Firstly, this involves the issue of usability. For desktop computers nowadays, we can easily determine the functionality of a structure based on its shape, and at the same time, the different shape interfaces also achieve a certain degree of foolproof effect. As long as it's not for miraculous wiring with great effort, people with a little common sense will not plug DP into the power supply or network cable into the USB.

But once USB C unifies these interfaces, wiring becomes particularly difficult. Considering that the interfaces with different functions are closely related to the bandwidth allocation of the backend bus, we cannot require brands to equip each interface behind the computer with four independent PCIe 4.0 channels. All unified interfaces will only increase the difficulty of boundaries.

In addition, the devices that need to be connected to the USB C interface also have different requirements for bandwidth and speed. For example, external graphics cards require 40Gbps of lightning protocol, external hard drives require 10Gbps of high-speed access, USB C keyboards require 5W of charging power and 2.0 USB speed, and charging Bluetooth headphones do not require data connection, only 18W of power supply.

Of course, we can equip all the above devices with fully functional Thunderbolt 3 cables, but if the 4 cables are added together, it will definitely not cost 800 yuan. Considering cost, both consumers and brands require USB C cables with different functions and grades. This will lead to another phenomenon: the cable can be plugged in, but the data is not available.

This kind of scenario where cables can be plugged in but cannot be used almost never happened in the past, but with the popularity of USB C, this phenomenon has become increasingly common. For the simplest example: You bought a USB C Hub that works when plugged into a computer, but it doesn't respond when plugged into a Switch. Alternatively, you can rummage through the boxes and cabinets to find a USB C charging cable that was included when buying headphones. After connecting your phone and computer, you realize that this cable can only be used for charging, not for flashing.

As a universal interface, USB C naturally has its own advantages, but the versatile USB C interface has also been defeated by the contradiction between diversity and practicality. It is undeniable that in the future, USB C will continue to play multiple roles and become the universal serial interface of the new era. But I hope everyone can stop and think for a moment while advancing the USB C process in the design process. Do we really need to use USB C as a universal bridge for all things.

Source: Lei Technology