USB audio input is a standard

USB-C: the all-rounder Update

One cable for everything, that is the basic idea behind USB type C. The small, twist-proof connection takes up little space and therefore also fits in super slim notebooks and thin smartphones. USB-C not only transports data, but also video and audio signals and even charging current for smartphones, tablets or notebooks.

Benefits of USB-C

The most noticeable and practical advantage of USB-C is the twist-proof plug - it can be plugged into the socket in any direction and works in both orientations. The annoying fiddling with conventional USB plugs is no longer necessary.

In addition, the USB-C socket is an all-rounder because it combines several functions at the same time: It is a classic USB port for data transfer as well as a connection for keyboard and mouse, DisplayPort for external monitors, HDMI for TV sets, replacement for audio Jack socket for headphones and charging socket for mobile devices.

Another advantage is the fast data transfer, because thanks to USB 3.1 SuperSpeed ​​USB 10 GBit / s, data flows twice as fast as via USB 3.0 - even faster on new MacBooks thanks to Thunderbolt 3. And although USB 3.1 has not yet arrived in all PC chipsets, the data rate of USB 3.1 is to be doubled again with USB 3.2. On the USB-C ports that are not yet capable of SuperSpeed ​​with 10 Gbit / s, you have to be content with SuperSpeed ​​and 5 Gbit / s, in rare cases even only with USB 2.0 speed and 40 MByte / s. Which version is supported depends on the respective device.

If you want to operate devices or USB sticks with a type A plug on a notebook, smartphone or PC with a type C socket, you need an adapter.

USB 3.2. doubles the transfer rate to 20 Gbit / s

Although the 10 Gbit / s speed level introduced a few years ago with USB 3.1 has not yet arrived in all PC chipsets, the next level is already around the corner: USB 3.2 doubles the data rate again, so that up to 20 Gbit / s over USB cable flow.

The latter, however, has to be a cable with a USB-C connector at both ends. With the new level, the data rate of a link is not doubled as before, but instead a second pair of wires in fully wired USB-C cables is used in parallel. This means that there are no new restrictions with regard to cable length.

In USB-C cables with a type A or B connector on the other side, the second wire pair (and the required contacts in the connector) is missing, so that there is still a maximum of 10 Gbit / s. By the way, the second pair of wires has already been used in USB-C docking for DisplayPort signals; 20 Gbit / s is not possible even in such scenarios.

New names with the introduction of USB 3.2

So far there has been a lot of confusion because USB 3.1 already includes several speed classes: Gen 1 (5 GBit / s as with USB 3.0) and Gen 2 (10 GBit / s). It doesn't get any better: The 20 GBit / s level of USB 3.2 does not listen to Gen 3, but to Gen 2x2. This is technically correct, but not very user-friendly.

The standardization committee USB-IF (Universal Serial Bus Implementers Forum) is officially promoting the three terms SuperSpeed ​​USB, SuperSpeed ​​USB 10 Gbit / s and SuperSpeed ​​USB 20 Gbit / s with immediate effect. The previous 10 Gbit / s name SuperSpeedPlus, however, is already obsolete again, although the word “SuperSpeed ​​+” still adorns the associated logo.

Thunderbolt 3 becomes USB 4

Two interfaces become one: Intel and the USB-IF (Universal Serial Bus Implementers Forum) standardization committee have announced that Intel is handing over the Thunderbolt protocol specification to the USB-IF. As with USB, interested manufacturers can now produce suitable chips without having to pay license fees - that was necessary with Thunderbolt. USB-IF will use freshly gained know-how to raise the upcoming USB version 4 to a data transfer rate of up to 40 Gbit / s.

There are only vague statements about the technical implementation. USB 4 may not be much more than Thunderbolt 3 with additional lane bonding for USB 3.2, which previous TB3 chips are not capable of. The declared goal would be for two devices with USB-C connectors to negotiate the best possible speed in each case, across all previous levels down to USB 2.0 - and also the desired backward compatibility with Thunderbolt 3.

Thunderbolt 3 functions and bandwidth in turn solve the docking problem for notebooks and tablets: With USB-C docking via old modes, the two data lines are each assigned to a fixed task, which restricts both DisplayPort and USB capabilities. Thunderbolt 3 not only brings a higher bandwidth, but also a more flexible allocation of it. It is still unclear when the first devices with USB 4 controllers will be available.

USB certificates

The USB-IF has also announced that the service provider DigiCert will take care of key management and other cryptographic tasks related to the additional standard USB Type-C Authentication. With the digital certificates, the USB-IF creates an open standard for security: If a device certified as a USB power supply unit wants to slip a USB-HID keyboard to the host, for example, this indicates compromised hardware and the host can refuse the connection. Companies, on the other hand, can only allow selected peripherals on company notebooks without the admins having to completely switch off the sockets for security reasons.

Finally, manufacturers can generally also certify third-party components and allow them to be operated on their own hardware. If this reminds you of Apple's MFI program (made for iPhone): According to USB-IF boss Jeff Ravencraft, Apple was a driving force behind the authentication standard.

Connect older devices using a USB-C adapter

To use older devices with USB-A plugs on USB-C sockets, adapters are required. Passive adapters only connect the contacts of a type C plug required for USB 2.0, USB 3.x and the power supply to the type A socket. Like comparable adapters from USB-C to USB with type B input, they serve as an electromechanical bridge.

DisplayPort adapters for type C jacks have more intelligence of their own; you use the "Alt Mode" of USB-C (see info box below). In order for a monitor to work on USB-C in Alt Mode, the signal source - i.e. the notebook or PC - must output DisplayPort signals to its USB-C sockets.

Additional converter chips in the alt-mode adapter process DisplayPort signals for HDMI 1.4 or even HDMI 2.0 with 4K resolution. Most of these active adapters are currently satisfied with Full HD resolution and only transmit 4K signals with a refresh rate of 30 Hz - even HDMI adapters that are labeled as "4K-capable".

Some monitors have their own built-in USB-C port. They use it to receive video signals from USB-C sources - currently these are exclusively DisplayPort signals in the Alt Mode of USB-C.

USB standards
Surname fastest transfer mode Gross transfer rate (Pracis)
USB 3.2 (USB 3.2 Gen 2x2)
SuperSpeed ​​USB 20 Gbit / s 20 GBit / s (1,800 MByte / s)

USB 3.1 (USB 3.1 Gen 2) SuperSpeed ​​USB 10 Gbit / s
10 GBit / s (> 900 MByte / s)
USB 3.0 (USB 3.1 Gen 1) SuperSpeed ​​USB 5 GBit / s (480 MByte / s)
USB 2.0 High speed 480 MBit / s (36 - 44 MByte / s)
USB 1.0 FullSpeed 12 MBit / s (1 MByte / s)
USB 1.0 LowSpeed 1.5 MBit / s (keyboard, mouse)
... for comparison
Thunderbolt 3 / NVMe SSD PCIe 3.0 x4 40 GBit / s (> 3 GByte / s)
Thunderbolt 2 PCIe 2.0 x4 20 GBit / s (> 1.3 GByte / s)
PCI Express 3.0 x1 10 GBit / s (1 GByte / s)
SATA 6G 6 GBit / s (560 MByte / s)
Gigabit Ethernet 1 GBit / s (110 MByte / s)
WLAN 802.11ac MIMO close 4 x 4 400 MBit / s (50 MByte / s)
DSL 50 Mbit / s 50 MBit / s (6.3 MByte / s)

How do I know what my USB Type-C device can do?

Not every device and every USB-C socket have the same range of functions. For example, smartphones with a USB-C socket often only offer a charging function and data transfer in the high-speed mode of USB 2.0, i.e. at a rather slow 480 Mbit / s. On notebooks with several USB-C sockets, one port is sometimes suitable as a display connection, while the others are only suitable for data transfer or for charging mobile devices. USB-C sockets on desktop PCs often only supply power and data, but neither DisplayPort signals nor a higher charging capacity.

For easier identification, there is an extensive set of logos that describe what the respective Type-C device can do. Unfortunately, not every manufacturer uses these logos - then only a look at the data sheet or manual will help.

In practice you will probably have to try something, since it depends not only on the ports of the devices involved, but also on the ability of the cable. For example, you need special type C cables for higher charging power.

HDMI signals via USB-C

Although many Type-C docks available today provide HDMI sockets for monitors or televisions, the HDMI Alternate Mode is by no means used in the docks. One reason: The old HDMI specification is still too new, which is why there are no corresponding controller chips yet.Instead, the video signals are transmitted via DP-Alt and then converted to HDMI in the adapter. Since the established DP-Alt already supports the latest iteration DisplayPort 1.4 and the display port signals in the adapter can be converted to an HDMI 2.0 socket, there is little incentive for device manufacturers and chip developers to use HDMI-Alt in the current one To use form at all.

Alt modes from USB-C

USB-C connectors can do more than just USB data transmission and power supply, namely so-called alternate modes. Such deviating pin assignments include DisplayPort (DP-Old), MHL (MHL-Old), Thunderbolt 3 (TB-Old), PCI Express (PCIe-Old) and, more recently, HDMI (HDMI-Old). Some pins may not be switched for safety reasons or because they have defined functions. However, 10 pins are available for the Alt modes.

A prominent example of an Alt mode is DP-Alt: This provides that the four DisplayPort lanes are distributed over the RX / TX pairs and the additional AUX channel (AUX +, AUX-) runs via SBU1 and SBU2. This full configuration is only required for particularly high resolutions - even 4K resolution at 60 Hz can be sent via just two DisplayPort lanes (DP lanes).

However, the 4K video signal can only be sent over two DP lanes if the lanes are running in HBR3 mode with a higher bandwidth. This also explains why the USB speed sometimes drops back to USB 2.0 when using a 4K monitor at 60 Hz instead of 30 Hz.

There is also a second old DP circuit that is suitable for docking solutions thanks to parallel operation. In parallel operation, for example, USB 3.x signals and DP video signals can be transmitted at the same time.

USB-C audio and fast charger

The specification for USB-C audio has meanwhile received an important update: It is now possible to output digital audio signals and feed in power at the same time via a USB-C switch. This is important for smartphones, which usually only have a USB-C socket - and no longer a 3.5 mm jack socket.

After all, USB-C power supply units with the new Fast Charger logo should be available in stores by the end of the year. The latter is a bit misleading: even with the older logo for certified charger, fast charging is possible because, thanks to USB-PD, they can output more than 5 volts. Fast-Charger-certified power supplies also comply with the PPS (programmable power supply) sub-standard, which allows power supplies not only to provide fixed levels above 5 volts, but also to run through dynamic, wide voltage intervals. The latter only works if a smartphone explicitly supports and requests this - which should be the case more frequently in the future, because it greatly simplifies the structure of the charging electronics in the smartphone, thereby lowering component costs and also leaving more space for the battery and the like.

USB-C adapters and docks

The new notebook only has USB Type-C as the only connection and the monitor, USB drives, keyboard, mouse and printer should be connected to this: Hubs or mini-docks with a USB-C connector at one end help here and wear the missing outputs on the other. In the post:

Make many out of one: USB-C adapter tested

We tested various USB-C hubs from adapter providers as well as original accessories from Apple, Asus and Samsung on various devices.

Charge your mobile phone or notebook to USB-C

A new feature of USB-C is the ability to switch between the feeding and consuming roles of the power supply. A type C USB socket can therefore also be used as a charging connection and is already established as such on tablets, smartphones and even notebooks.

Many notebooks and PCs with type C sockets provide higher power to feed peripheral devices. USB 2.0 was only designed for 2.5 watts (5 V / 0.5 A), USB 3.0 at least for 4.5 watts (5 V / 0.9 A). USB-C hosts can deliver up to 15 watts (5 V / 3 A); that's enough to charge tablets and smartphones. 7.5 watts (2.5 V / 3 A) are usually sufficient to operate USB 3.1 SSDs. For notebooks you usually need more charging power - this is made possible by USB Power Delivery (USB-PD).

Power supply via USB
specification Voltage current power
USB 2.0 5 V / 0.5 A 2.5 W.
USB 3.0 / 3.1 5 V / 0.9 A 4.5 W
USB BC 1.2 5 V / 1.5 A 7.5 W
USB type C 5 V / 3 A 15 W
USB PD 5 ... 20 V / 5 A 25 ... 100 W.

What is USB Power Delivery?

Regardless of the transfer of USB and video data, (micro) USB sockets have established themselves as the standard for charging smartphones and tablets. Unfortunately, a proliferation of fast charging processes has developed. In order to contain this and at the same time cover the higher power requirements of notebooks, USB-C charges connected mobile devices with up to 3 amps.

At the same time, the supplementary specification USB Power Delivery was developed: USB-PD officially allows higher voltages - apart from 5 V these are 9 V, 12 V, 15 V and 20 V. At 20 V, even up to 5 A can flow, which is a remarkable overall Gives 100 watts; For the highest performance, however, special type C cables are required. An official extension of the USB-PD standard beyond 100 W is not planned.

The communication between the devices involved about the required charging power takes place via the CC pins of the USB Type-C connector. This is why USB-PD does not work with older socket formats.

In everyday life, the various possible voltages cause confusion, because not all power supplies and devices can be freely combined. In addition, nowhere does the USB-PD specification dictate how devices should behave when power supply and demand do not match. The specification ensures that nothing breaks, because voltage levels beyond the USB-typical 5 V are explicitly requested or only provided on request. However, there is no guideline according to which PD-capable Type-C notebooks must be charged on a smartphone power supply unit that can only provide 5 V. Therefore, the USB power supply units and devices cannot be combined arbitrarily until further notice.

Special cable for USB-C

With the new USB-C sockets, there are also new cables. Typically, communication using the Type-C capabilities between the two endpoints takes place using any Type-C cable. But there are cases in which the cable itself has to communicate that it can do more than usual. These cables are called electronically marked (EMCA: Electronically Marked Cable Assembly). This category includes Type-C cables with thick cross-sections, which are intended for USB-PD power supply and can withstand the full 5 A instead of the usual 3 A.

In addition, Type-C cables, which enable SuperSpeed ​​USB 10 Gbit / s data rates thanks to better shielding, must expressly communicate this to their endpoints; otherwise only 5 GBit / s run over the cable.

All adapter cables that only have a Type-C connector and the others in non-USB format (e.g. DisplayPort connector) also fall into the EMCA category. Here the cable has to tell the Type-C device that it is explicitly only intended for this Alt mode. (uk)