USB Type-A, USB Type-B or rather Micro-USB, Mini-USB and USB Type- C? Hardly any other standard is as complicated as the USB standard. But which plug fits what and what is the difference between the different connections?

USB: One standard, many types

USB is not just USB. What was actually intended as a simplification for the consumer when the “Universal Serial Bus” was introduced – namely as a standard interface for many devices – has meanwhile produced a large number of different plugs, sockets and versions.

From Around the year 2000, USB 2.0 gradually replaced the older USB 1.0 specification as the data transfer rate standard. Instead of a maximum of 12 Mbit/s, up to 480 Mbit/s could effectively be transmitted. USB 3.0 has been spreading so slowly since 2011 with a maximum effective data rate of 4000 Mbit/s. But different plug and socket versions also contribute to the confusion. Therefore, if we want to talk about the characteristics of mini-USB and micro-USB, we also have to deal with different USB types.

USB Type-A: The actual standard

USB Type-A is the most common USB connector. It can be found on almost every USB stick, mouse, keyboard and most other USB devices. The plugs themselves are flat and wide and can only be plugged into the matching sockets in one direction.

Everyone knows the USB Type-A connector.

Image: © Thinkstock/Hemera/Pradheep Vepur 2017

USB Type-B: A almost forgotten plug

USB Type-B connectors are rarely used and have almost completely disappeared from devices. However, there are often older printers or fax machines that have one of the tall USB type B connectors. However, suitable connections are rarely found on computers or other devices, which is why a USB type B to type A cable is usually used.

USB Type-B is rarely used anymore.

Image: © Thinkstock/amana images RF/DAJ 2017

Mini-USB: 60 percent smaller than USB

Some camera models, for example, are charged via the mini-USB connection.

Image: © picture-alliance/Wiktor Dabkowski 2016

Mini-USB connections according to the USB 2.0 specification were introduced in the year 2000, especially for use in smaller devices such as cameras or MP3 players. At times, these were also available in different versions: Type A, B and AB. However, Mini-A and Mini-AB disappeared from the market again in 2007 – since then there has only been Mini-B. These are used in peripheral devices, such as the camera or the MP3 player.

Compared to conventional USB plugs, mini USB plugs are around 60 percent smaller. Instead of 12 x 4.5 millimeters, they only measure 6.8 x 3.0 millimeters. But they have one pin more than the large USB plugs. However, this ID pin still has no function with mini-USB. As a result, the connections often only work in one direction – for example to send or receive data or to charge a peripheral device. Mini-USB must guarantee a minimum number of 5000 mating cycles, i.e. 5000 insertion and removal processes. Because the contacts wear out over time.

Micro USB connector: charge & Transfer data

Most smartphones currently use microUSB.

Image: © TURN ON 2016

The micro USB standard is even smaller. At 6.85 millimeters, micro-USB plugs are slightly wider than mini-USB plugs, but they are only 1.80 millimeters high. In contrast to mini-USB, there are micro-USB plugs in the versions type A and type B, the sockets are also available as micro-AB. Many smartphones, such as the Samsung Galaxy S7, use a Micro-USB-B connection for charging and data transfer.

Micro-A connectors are completely rectangular, while Micro-B connectors end trapezoidal. In addition, different colors are used: white for Micro-A, black for Micro-B and gray for Micro-AB. Micro-A is used on the host side, Micro-B is plugged into the peripheral device and Micro-AB is intended for connecting two end devices without a PC.

Like Mini-USB, Micro-USB has five pins, but the ID pin serves a function here. It is responsible for marking whether it is a micro-A or micro-B connector. Unlike mini-USB, micro-USB connections can work in both directions and perform multiple functions at the same time. You can charge a smartphone via Micro-USB and at the same time transfer photos, for example. The smaller plugs also have to last longer than mini-USB: the standard stipulates 10,000 plugging cycles.

USB 3.0, USB 3.1 & USB 3.2: Faster data transfer

The new USB 3.0 standard was developed in 2008 in order to be able to transfer even more data at even greater speed. This transfers data at a speed of up to 5 Gbit/s and is mainly used for external hard drives. USB 3.0 plugs and ports can usually be recognized by the blue color inside.

The 3.0 standard reintroduced a new, extremely flat shape for micro-USB plugs. A faster specification, USB 3.1, was released in July 2013. Compared to 3.0, the new version doubles the speed to 10 GBit/s. USB 3.0 was later renamed USB 3.1 Gen 1.

Standard USB 3.0 (left) and Micro USB 3.0 (right).

Image: © Thinkstock/iStockphoto/mariozupancic 2017

The maximum data rate for USB 3.2, adopted in summer 2017, is up to 20 Gbit/s. Two channels each with 10 GBit/s are used for this. In 2019, as part of the new standard, the older versions were combined under USB 3.2, which will henceforth be referred to as “USB 3.2 Gen 2×2”. Both “USB 3.1 Gen 1” and “USB 3.1 Gen 2” are now listed under “USB 3.2 Gen 1” and “USB 3.2 Gen 2”.

USB Type-C: The new plug for everything

In order to get rid of the tangle of plugs, a new type of plug has been introduced since 2014 with USB Type-C. This has a completely new shape and does not fit older USB ports. The difference between normal USB, Mini-USB and Micro-USB does not apply with Type-C, as there is only one plug and one socket for everything.

Several manufacturers are currently working on making USB Type-C a establish a new standard. New smartphones such as the Samsung Galaxy S8 or the LG G6 are already delivered with a USB-C socket. This offers several advantages. The point-symmetrical shape of the plug, for example, is practical in everyday life, and it doesn’t matter how it’s plugged into the socket.

Wants to establish itself as a new standard: USB-C.

Image: © YouTube/ Mitch Mueller 2019

USB-C is associated with the long-term hope of completely replacing the previous USB-A and USB-B connections. USB-C not only enables significantly higher speeds.

Thanks to improved energy transfer of a maximum of 100 watts, 20 volts and 5 amperes, mobile devices also charge faster via USB Type-C than via Micro-USB B. The standard also supports DisplayPort and 4-channel sound (loudspeakers and microphone). In practice, this means that USB Type-C can also be used to connect displays in the future and could thus replace HDMI in addition to DisplayPort.

Despite these advantages, USB Type-C is far from established as a Established industry standard. However, this is likely to change in the next few years.

More about USB-C at SATURN

Summary

• USB Type-A: Common in USB sticks, mice, keyboards and many other devices. Plug flat, wide and only fits in one direction.
• USB Type-B: Only rarely used anymore, often found in older printers. A type B to type A cable must often be used for connection to the PC.
• Mini-USB: About 60 percent smaller than the normal USB connector
• Micro-USB: A little smaller than mini-USB
• USB 3.2 offers speeds of up to 20 Gbps using two channels
• USB-C is compatible with all USB specifications and has better power transfer. Devices can be charged faster via USB-C.