USB Type-C: What you need to know, the confusions to avoid

The USB connector Type-C was unveiled a year ago, and then ratified six months ago, but it is beginning to materialize this month and should quickly democratize. The opportunity to come back on some subtleties and anticipate some potential confusions.

The standards often contain subtleties that are likely to escape the layman, especially in the field of connection. In essence, the connector, i.e. the form of the socket, the interface, i.e. the communication protocol, should be distinguished.


It must be said that we are the first, the specialized media, to endure abuses of language so as not to divert our readers. Thus, it was sometimes referred to as “VGA port”, while VGA signals could borrow a D-Sub-15 connector, in most cases, but also sometimes five BNC plugs. More contemporary: The concept of “HDMI” refers to both the connector and the “High Definition Multimedia Interface”. The MHL output of some smartphones, for example, transmits an HDMI signal (among other things) through USB connectors.

USB Type-C is not USB 3.1

To return to the USB, the Type-C only designates the connector. It has been designed in conjunction with USB 3.1, and by the same USB 3.0 promoter Group, but many devices with USB C ports will be only USB 3.0 or USB 2.0 or even USB 1.1. An audio DAC For example does not need any more.

The single-size USB Type-C connector succeeds the three sizes of USB type-A and type-B (micro, Mini and full format). Similar in size to a Type-a micro USB connector, the USB C thus brings a leveling down in terms of clutter. It contributes to the design of ultra-thin laptops.

It is also and above all reversible: one can connect it indifferently in one direction or the other. But he still has a gender, male or female.


The alternate Mode, reserved for USB C

The USB C Connector finally has more contacts, paving the way for other innovations.

The USB 3.1 TYPE-C actually leads to an increase in throughput, but you can benefit from the bandwidth range from 5 to 10 Gb/s with traditional 11-pin Type-A USB connectors. The new USB power Delivery 2.0 standard, which carries 100 W electricity that can be delivered in USB, also accommodates a USB connector. It also makes the power supply bidirectional: A transformer can power a laptop and a laptop computer can power an external device through the same port.

But the latest, most significant innovation, calls for extra pins. The USB Type-C brings the alternate Mode, which allows to reassign the pins of the four channels of a connector to establish all kinds of connections. It makes the USB connection truly universal. At Date, the VESA has formalized the DisplayPort alternate Mode, which allows an audio-video signal to be broadcast on a USB C-connector cable.

The USB 3.1 Gen 1 trap

To conclude a potential trap, that of the “USB 3.1 Gen 1″, which benefits from all the aforementioned innovations, but which operates the same data transfer Protocol as USB 3.0, and capped at 5 Gb/s.

The best way to identify throughput will be to refer to the following terminology: SuperSpeed for 5 GB/s and SuperSpeedPlus for USB 3.1 Gen 2 to 10 Gb/s.

Anyway, USB remains true to the principle of compatibility. Logically, a USB 1.1 device can be connected to a USB 3.1 interface, but on a physical level it will sometimes be necessary to use passive adapters to switch from USB A to USB C. It is nevertheless a first for the USB, created nearly 20 years ago (in 1996), and thus the beginning of the first transient phase of this connection, which could spread over several years.