The new USB plug does not pass the way! Therefore, take a closer look. Where does it come from? The doubling of the data rate compared to the previous model?
By Andreas Aigner, Business Development Manager of Würth Elektronik eiSos
The latest generation of USB makes the name “Universal Serial Bus” a great honor, because in the telecommunications, USB 3.1 and the new connector type C will be established as a large area as a standard. But not only telecommunications and consumer products require higher power supply and faster data transmission. The same applies to industrial applications, such as portable measuring and test equipment.
Therefore, a closer look at the plug design is worthwhile: How is the doubling of the data rates to 10 GBit / s – compared to USB 3.0 – and how does the specification USB 3.1 differ from the previous generation?
The new USB3.1 connector in detail
Firstly, EMC performance has been improved by changing the shielding. Second, modifications to the protocol result in approximately 20 percent more bandwidth. USB 3.0 uses an 8b / 10b encoding. With USB 3.1 one has switched to a 128b / 132b coding scheme. Simultaneously, the tolerable jitter was decreased from 200 to 100 ps on all transmit and receive lines to reduce the bit error rate (BER) to 10-12.
Impact on the connector types
With type A connectors, the hardware is slightly modified due to the amplified shielding, but the connector remains down-compatible. Two pins for the power supply and the recognition of the plug-in state are added to the power-delivery-compatible plug.
The connector type B as well as the micro connectors are identical to the specifications of USB 3.0, but they have additional shielding.
Completely new is the plug Usb type C: by 24 pins it is pluggable on both sides and also supports power delivery. The socket of type C can also be plugged on both sides. This eliminates the problem of the “Falschherum plug” for the first time. With a plug-in force of 5 to 8 N, the Type C connector not only requires the least amount of force required to plug it into the socket; it is – like the Micro B – designed for 10,000 plug-in cycles.
Pin assignment for type C
The pin assignment of the C type connector is shown in Figure 1 (Picture gallery). Pins A1 to A12 correspond to the pins B12 to B1 in descending order, whereby the associated plug can be used as desired. The pins A1 / B1 and A12 / B12 for the ground connection as well as A4 / B4 and A9 / B9 for the bus voltage together with pins A6 / B6 and A7 / B7 as a data pair and a corresponding adapter ensure the downward compatibility to USB 2.0. The A2 / B2 and A3 / B3 (Super-Speed Transmitters) as well as A10 / B10 and A11 / B11 (Super-Speed Receiver) pins can also be connected with an adapter to ensure compatibility with USB 3.0. The pins A5 / B5 serve as a configuration channel and the pins A8 / B8 for sideband use – this is the main difference that makes USB 3.1.
A fully populated type C connector has only 22 pins, since the contacts B6 and B7 are not available for avoiding interferences and disturbances due to too tight conductor routing. The six flanges in the housing of the 5-A socket hold the plug securely.
USB plug under the magnifying glass, part 2
Würth Elektronik supplies the sockets »632723×00011« for SMT as well as THT mounting on 1.0 and 1.6 mm printed circuit boards. Compared to other bushings available on the market, these are longer: due to the larger bearing surface they offer a greater holding force. The nickel shielding is 200 μm twice as thick as most of the competition products. Under the designation »632712000011« the matching 3 V connectors are available. Würth Elektronik also offers Type A connectors (632121300001). Because the Power Delivery Detection function also provides a power supply of 20V in both directions, they are ideal for connecting displays, including 4K / Ultra-HD resolution (3,840 × 2,160 pixels) with one Refresh rate of 60 Hz. If all data lines are used for the transmission of the video signal, even a 5K resolution (5,120 × 2,880 pixels) is possible. Both the Type A and Type C connectors are TID listed.
Differences in cable types
Differences to USB 3.0 and USB 3.1 are also available with the cable: instead of nine cores with USB 3.0 now under the sheathing of cable type C now 15 wires are hidden. This also affects the specification of the cable length: USB 3.0 Super-Speed, also known under the name USB 3.1 Gen1, is still 3 m allowed, it is with USB 3.1. Super-Speed +, also known as USB 3.1 Gen 2, only a maximum of 1 m. Würth Elektronik leads the corresponding cables in the program.
For the use of USB 3.1 in the industry, for example, for sensor real-time monitoring, it is above all the fact that no special cables are required anymore! Especially for measuring setups the cable diversity is thereby reduced. The faster data transmission and the possibility of plugging the plug as desired into the socket reduce the time required. The option that the connected devices can load each other will also be of great use in maintenance, where a portable measuring device and a tablet are often required.