Without USB-C in the vehicle, nothing works?

Why you should not do without USB-C in your vehicle, the challenges associated with integration into the vehicle and the possible solution approaches 

The digital transformation is in full progress in all areas of life, including the automotive industry. Mobile end devices are our daily companions and we can no longer imagine life without them in the car. As a result, we take our office and living room with us everywhere we go. At the same time, we do not want to do without energy- and data-intensive applications. Quickly charging a laptop or cell phone in your vehicle – this is considered “normal” today. To ensure this mobile flexibility, increasingly faster charging and data transmission systems are needed in the vehicle. USB Type-C interfaces are the new standard.

You want to integrate USB-C into the vehicle? Learn everything you need to know about USB Type-C, what you should consider when integrating it into the vehicle, and a possible solution approach.

After A comes C – the advantages of USB-C in the vehicle

USB interfaces are an absolute must-have in vehicles today. USB means “Universal Serial Bus” and makes it possible to create a connection between a computer and external digital devices. Via these USB interfaces, it is also possible to retrieve data from mobile end devices in vehicles by means of a suitable cable. At the beginning, this data was mostly music files on MP3 players which could also be managed and played by the vehicle’s music system. Pleasant side effect: the devices are charged simultaneously. Nowadays, the USB connection is also often used to show apps and contents of smartphones on the large displays of the vehicles (Apple CarPlay, Android Auto, MirrorLink).

USB Type-C is the new standard. This offers greatly extended possibilities compared to its predecessor USB Type-A.

Greatly extended possibilities thanks to USB-C

Power Delivery
In addition to the already established charging functions of Apple, USB 2.0 and USB 2.0 BC 1.2, the new Type-C standard also enables a USB Power Delivery (PD) charging function of up to 100 watts. Furthermore, this standard supports USB PD 3.0 (PPS – Programmable Power Supply), known as “fast charging”, which is used especially in new generations of mobile end devices.

New USB data transfer protocol
USB Type-C also benefits greatly from the new USB data transfer protocols. In addition to the common USB 2.0 Highspeed variant of 480 Mbps, the new standard also includes protocols such as USB 3.2 Gen1 SuperSpeed with a transfer rate of up to 5 Gbps and USB 3.2 Gen2 SuperSpeed+ with a transfer rate of up to 10 Gbps.  

USB Alternate Modes
USB Alternate Modes are also supported, which enable a partly native transmission of video signals such as HDMI, Display Port, MHL or even Thunderbolt via USB Type-C adapters and cables. For transmission, for example, some kind of desktop mode function must be integrated into the software of the mobile device, which allows the connection of external peripherals such as a monitor, mouse or keyboard to the device and use in a similar way to a PC. Especially in the area of rear seat entertainment, this opens up numerous new application possibilities, such as setting up a mobile workstation or using an integrated display for a perfect cinema feeling.

Advantages at a glance

Challenges during integration into the vehicle

The integration of USB Type-C modules into the vehicle is accompanied by some challenges. Due to the increased charging power of up to 100 watts, the charging electronics generate a lot of heat inside the enclosed modules when standard charging modules are used. To counteract this heat development, the volume of the module could be increased. However, this extra installation space is usually not available in the dashboard and is therefore always hotly contested between the different development departments at the OEMs.

Solution approach

A remote customer interface would be the ideal solution. In this context, remote means that the charging electronics are relocated from the module to a central control unit, and the actual customer interface (USB Type-C socket) is connected via a specially developed cable, thereby drastically reducing the installation space required in the dashboard and dissipating the waste heat elsewhere.

The length of the transmission distance is limited, however, since a certain voltage drop occurs over the length of the cable, which depends on the current level and the stranded wire cross-section. This leads to the USB signal being increasingly weakened and perhaps no longer conforming to the standard at the customer interface.

For this reason: “Hands off cheap cables”

Standard consumer adapter cables are usually only designed for lengths up to a maximum of 1 meter due to their small cross-section and simple cable structure.

Longer transmission distances require specially developed cables with appropriate stranded wire cross-sections for high charging currents and high data rates. Such cables are necessary for both internal cabling (from the source to the customer interface) and external cabling (from the customer interface to the consumer device) since both cable sections make up the entire link.

For this purpose, the USB.org specifies a maximum voltage drop of 250 mV for the complete transmission link (source to sink) to ensure proper functioning of the signal transmission. This is the only way to maintain the signal integrity described in the USB specifications.

As soon as this signal integrity can no longer be reliably ensured, malfunctions in the data communication or a pseudo-charging function quickly occur, in which a charging process is displayed on the device, but the required charging current is no longer made available for charging in accordance with the regulations.

With such an optimized system, it would also be possible to implement in-vehicle cabling over longer distances, such as a point-to-point connection between control units or remote customer interfaces for data and charging functionalities.

Conclusion and recommendation

To meet the latest standards, the charging currents of mobile devices will continue to increase in the future. A power supply with 5 A or up to 20 V, data rates far above 1 Gbps and further signal forms such as alternate modes with simultaneously less and less installation space are current targets.

At present, it is hard to find a connector system that combines both functionalities in just one cable.

The intelligent combination of an established consumer connector with an automotive-suitable housing design results in a USB-C connector system that is an ideal solution for upcoming vehicle generations.

The high requirements of the automotive industry and the continuously increasing data rates do not normally allow for “cheap solutions”. Therefore, the following applies: Do not skimp on quality and invest a few cents more in the design of a new system. This is the only way to ensure a permanently flawlessly functioning data link.