Wednesday, August 10, 2022

All about the USB Type-C connector: one for all


The USB standard has become popular for a long time. There is simply no user who is not familiar with it. From this, the step taken by the developers to switch to a completely new connector looks even more bold and complex. Did he justify himself?

A small revolution in the world of USB
USB Type-C or USB-C, by the way, both versions of the name are correct – a universal connector of the USB standard, curated by the international organization USB-IF. The first release was released in 2014, and the latest and current 2.0 specification is dated August 2019. USB-C is intended to replace all existing standard USB connectors.

The specification lists the design advantages:

the ability to use in thin gadgets (ultrabooks, smartphones, etc.) due to compactness – the height of the USB Type-C socket does not exceed 3 mm;
independence from the orientation of the plug – can be connected by any side;
independence from the direction of connection (host and device) – the same connector on both ends of the cable.
Don’t panic – according to the good old tradition, USB is backward compatible with older versions of the standard. Using an adapter, you will connect to a device with traditional Type A or Micro B. Of course, the data transfer rate and power level will be limited by the minimum version of the standard for interacting devices. The same Micro USB, characteristic of USB 2.0, will cut the bandwidth to 480 Mbps. More about this in the section on cables.

The most interesting begins just with throughput. Starting with USB 3.2 Gen2x2, aka SuperSpeed ​​20 Gb / s (more about the correct names here and here ), only USB Type-C is used.

In the future USB4 standard, which is already very close, there will be support for this connector only. If you need a speed of 20 Gb / s and above – only via USB-C.

Of course, in addition to the innovative design, the developers made a major update of the main performance characteristics. First of all, this is the expansion of the band and the increase in power. Additionally, it became possible to work with third-party interfaces. Let’s fix everything that “passes” through the USB-C connector:

DisplayPort Alt Mode (DP AM).
Read more about available alternate modes and trendy ways to connect your monitor here .

Monitor LG 29″ 29UM69G-B
An autopsy will show. USB Type-C Pinout
Let’s take a closer look at the connector. Outwardly, it is very different from its predecessors, for the first time having received a rounded symmetrical shape.

Don’t be put off by the lack of visible hooks on the plug and the numerous complaints about it. The connector has a locking mechanism in the form of latches on the plug and recesses for them on the socket. Such a lace can go in and out for a long time – the declared time between failures is 10,000 cycles. If an average of five connections are made every day, then it should be enough for 5 years of work.

The filling of the connector differs depending on the version. There are two types of socket: full-featured (Full-Featured Type-C Receptacle) and only supporting USB 2.0 (USB 2.0 Type-C Receptacle).

Let’s look inside the fully functional “mother” – there is a two-sided platform with 24 contacts, which are divided into several contact groups:

A1, A12 and B1, B2 – “ground”, located symmetrically;
A4, A9 and B4, B9 – power supply, arranged symmetrically;
A6, A7 and B6, B7 – a pair of pins for data transfer via USB 2.0, on the reverse side are mirrored;
A2, A3, A10, A11 and B2, B3, B10, B11 – two pairs of pins for high-speed data transfer via USB 3.2 and USB4, as well as alternative mode. Each pair of pins forms a channel (lane). On the reverse side, the channels have a mirror arrangement;
A5 and B5 – mirrored control contacts;
A8 and B8 are mirrored auxiliary contacts used to carry non-standard signals such as audio in alternate mode.
In a socket that supports only USB 2.0, at the discretion of the manufacturer, it is allowed not to separate the contacts of high-speed channels.

By the way, in the vast majority of smartphones, the USB-C port is only with 2.0. For example, on board the Honor 20 is just such a “stripped down” connector, while the older brother Huawei P30 is already fully functional.

6.1″ Smartphone HUAWEI P30 128 GB blue
The plug already exists in three varieties (we have not reached the cables yet):

full-featured (Full-Featured Type-C Plug);
кабель USB 2.0 (USB 2.0 Type-C Plug);
only for power supply (Type-C Power-Only Plug).
A fully functional plug contains a minimum of 22 pins:

Often, pins B6 and B7 are missing, since USB 2.0 only needs one pair of pins, and the socket has them on both sides. One of the control pins changes its purpose and is called Vconn. It is used to power a special electronic marking chip.

The USB 2.0 Type-C plug does not have pins for high-speed channels and non-standard signals (SBU1 and SBU2). This leaves a minimum of 12 contacts.

The “Power Only” type plug is rare in nature and contains nine mandatory pins (A1, A4, A5, A9, A12, B1, B4, B9, B12). The presence of the rest is optional.

They talked like a plug with a socket. Connection configuration
When contact is made, the configuration process starts. It occurs on the control pins (CC1 and CC2) and consists of several stages, including:

determination of the power source and consumer;
determination of plug orientation;
defining host and device roles;
USB Power Delivery (USB PD) communication;
determination of the nutrition profile;
setting of work in an alternative mode (if required).
The communication protocol is USB PD. It is he who is responsible for alternative modes and the correct choice of the power supply scheme for devices, which are discussed in more detail in the next section.

Unidentified coaxial objects
It turns out that you can get tangled in cables, even if there is only one and, moreover, universal. Most of the criticism of USB-C is related to the wires and their identification when buying. Several important criteria to simplify this task.

According to the specification, there are four types of cables:

full-featured (Full-Featured Type-C Cable) – full-featured plugs on both ends;
USB 2.0 (USB 2.0 Type-C Cable) – at both ends, plugs that support only USB 2.0;
integrated (Captive cable) – at one end is one of the types of USB-C plugs, and the other end is a non-removable part of the device, for example, a charger;
active (Active cable) – full-featured plugs on both ends.
On top of that, there is also Thunderbolt3 (TBT3). This is a separate story that goes beyond the scope of this material. Just note that these cables are labeled “Thunderbolt3” separately, and Full-Featured type plugs are used on both sides. A clearer picture should become when the USB4 standard, which includes TBT3 in alternative mode, is transferred to combat mode.

The first thing you should pay attention to when choosing is the supported standard. If the cable is planned to be actively used for data transfer, and even more so for connecting a monitor, then make sure that it is fully functional. This is not a trivial task, since not all manufacturers indicate this characteristic in the documentation (if any).

Here is an example of a great cable that only supports USB 2.0:

Cable round Belkin USB Type-C – USB Type C silver 1.2 m
In this case, the manufacturer is well-known and values ​​​​its name, so on the site, although not immediately, you can find that the maximum speed is 480 Mbps. There are many similar cables on the market.

And here is an example of a fully functional cable:

Cable round DEXP USB Type-C – USB Type C, USB black 1 m
If there is no information on the cable, but it is possible to visually evaluate it, then take a closer look at the plug. A fully functional plug must have a minimum of 22 or 24 pins. This will not happen in the USB 2.0 connector, it will smile at you a little toothlessly:

The second elephant on which the USB-C universe rests is the level of supported power. Moreover, both current and voltage can change: the USB Type-C cable should charge not only smartphones and tablets, but also laptops and even monitors. The operating voltage of a typical laptop charger lies in the range of 17-20V, and sometimes give the monitor all 100W! So USB-C, along with current support up to 5A, has to expand the boundaries of the supported voltage to 20V.

But how not to burn your favorite tablet, you ask? It resolves the same USB PD protocol by switching power profiles. After the connection is established, the devices try to agree on who can do what and who needs how much. For safety, the “conversation” will start with a voltage of 5V.

There are four levels: 7.5W, 15W, 27W and 45W. Each of them has its own voltage and current configuration. For example, for 15W, 5V and 9V options are available, and for power over 45W, 15V and 20V are added.

Cables are ranked by the amount of current they are rated for. There are three options: 1.5A, 3A and 5A. Always pay attention to this parameter! It is not allowed to connect the monitor with a cable less than 5A.

The third significant characteristic of a cable is its length. Below is a table of recommended passive cable lengths. Active cables contain additional transmitters to ensure signal transmission.

Don’t resist – try to have fun
Indeed, dealing with all the nuances of USB-C is not easy. But that’s the future of the USB standard, and it’s already here. You need to use its best features. Check the characteristics and compatibility of connected devices and cables, pay special attention to the latter. And then the force will definitely be with you.


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