The Universal Serial Bus (USB) port is perhaps the most commonly used and easily recognizable PC connectivity standard found on modern hardware. But as universal as the rectangular port and its various data transfer standards are, things have changed with the introduction of USB Type-C.
The smaller, reversible, oval Type-C connector is positioned to become the go-to port for both commercial and industrial computers, making the dream of a legitimately universal connection standard, at least in part, a reality. But like any tech change, there’s plenty of room for confusion with USB Type-C. Clarity isn’t helped by the varying data transfer rates of USB 3.0/3.1/3.2 and now USB4 and USB4 version 2. So what exactly is USB Type-C? How is it better than its predecessors, Type-A, and Type-B? And what do all the numbers mean?
Watch our Tech Edge video on the topic, and keep reading to find out. Please note, the text below includes information on some updates to the standard that were made after this video was created.
What is USB Type-A?
The most common and familiar USB connector shape is USB Type-A, which is currently used on the majority of computer equipment and peripherals (although that is quickly changing). It is also used on many other devices, including those that utilize its Mini-A and Micro-A variants (see feature image above). Gaining popularity in the mid 90’s, standard USB Type-A connectors are rectangular and have a distinct top and bottom. This requires them to be oriented properly in order to be plugged in.
What is USB Type-B?
The more square shaped USB Type-B is somewhat less common but is electrically identical to USB Type-A connectors. USB Type-B connectors are frequently used on printers, though they can also be found on some monitors and USB hubs. The Mini-B and Micro-B connectors, like their Type-A counterparts, are found on a wide range of electronics, from tablets and handheld GPS devices to cell phones.
What Is USB Type-C?
Type-C refers to the physical shape of the newest USB connector. (The USB Type-C connector shouldn’t be confused with the USB 3.1 or USB 3.2 standards.).
The USB Type-C connector is smaller than both Type-A and Type-B, oval-shaped, symmetrical, and reversible, meaning there is no “wrong way” to plug it in. This eliminates one of the most common complaints about USB Type-A. This newest USB connector is intended to replace the other existing USB form factors and provide a future-proof, fully-featured option for hardware designers to standardize on.
USB Type-C ports are becoming more and more common on mobile devices and consumer hardware. On the other hand, the industrial PC (IPC) market is just beginning to integrate USB Type-C ports into the latest generation of commercial devices.
Finally, we should note that while USB Type-A and USB Type-B have traditionally been written using the word “type” as shown, USB Type-C is increasingly being written as simply USB-C.
USB-C in the EU
The USB Type-C charging port has been mandated in the EU starting in 2024. This new law is a part of a broader EU effort to make products more sustainable, to reduce electronic waste, and make consumers’ lives easier. The first stage applies to small electronics like cell phones, digital cameras, tablets, and more. Medium electronics, such as laptops, have until 2026 to implement USB-C for charging.
USB shape vs. USB performance
It’s important to make the distinction between a given USB port shape, or form factor (like Type-A or Type-C), and the data transfer rates and power delivery available over that port. The generational standards that dictate the performance of USB are expressed as a numerical value, like USB 2.0, 3.1, 3.2, 4 and 4 v2
It all started back in 1996 with the introduction of USB 1.0 with a maximum data transfer rate of 12 Mbps (Megabits per second.) USB 2.0 maxed out at 480 Mbps. After those releases came versions with ever more complex numbers and capabilities. That’s led to a lot of understandable questions from users.
What is the difference between USB 3.2 Gen 1 vs Gen 2 and USB 3.2 Gen 2×2? What about USB4 and USB4 Version 2? Are these still the naming conventions?
USB data performance language usage guidelines
To simplify some of the naming conventions, theUSB Implementers Forum (USB-IF), the group that oversees USB standards development, has written guidelines for USB data performance language usage. Hopefully with this new document, consistent messaging and terminology on all USB content including product packaging, marketing materials, and advertising can be the norm. But that’s an evolving process that will take time. Keep reading for a breakdown of what the numbers in that document actually mean.
Breaking down USB data transfer rates
USB 5 Gbps: The specification name is USB 3.2 Gen 1, which used to be called USB 3.0. It offers a transfer rate of 5 Gbps, which is about 10 times faster than the USB 2.0 standard.
USB 10 Gbps: The specification name is USB 3.2 Gen 2 (released in July 2013) and it used to be called USB 3.1. It offers a transfer rate of 10 Gbps over the existing USB-A and USB-C connectors.
USB 20 Gbps: The specification name is USB 3.2 Gen 2×2 (released in September 2017) and it is available only for USB Type-C connectors using two-lane operation. It offers 20 Gbps transfer speeds.
USB 40 Gbps: The specification name is USB4 (announced in March 2019). It leverages the Thunderbolt 3 protocol and offers transfer speeds of 40 Gbps. (Note that the correct specification name is USB4 as defined by the USB developers. It is sometimes identified as USB 4 with a space.)
USB 80 Gbps: The specification name is USB4 Version 2.0 (released in October 2022). This updated specification extends USB4 speed and data protocol performance, enabling manufacturers to develop products that can deliver up to 80 Gbps transfer speeds.
USB Marketing Name
(Previous names listed in sub-bullets)
USB3.2 Gen 1×1
USB 3.1 Gen 1
USB 3.2 Gen 2×1
USB 3.1 Gen 2
USB 3.2 Gen 1×2
USB 3.2 Gen 2×2
USB4 Version 2
Watch our Tech Edge video on USB Generations. Once again, please note, the text below includes information on some updates to the standard that were made after this video was created.
USB A – visual differences
USB 2.0 (black inserts) and USB 3.0 (blue inserts)
Transfer speed differences are very important to understand when you’re connecting devices via USB. Since there is such a large jump in speed capabilities between generation 2 and generation 3 , some manufacturers distinguish faster USB ports with blue inserts. That is particularly true when they appear on the same device.Alternatively, the USB SuperSpeed logo or its “SS” abbreviation may be used to identify USB 3.2 ports, particularly when all USB ports on a given device are USB 3.2 (as on the CL100).
It should be noted, however, that while the data transfer rates of USB4 and USB4 version 2 and even 3.2 Gen 2 and Gen 2×2 are impressive, many devices aren’t yet capable of reading or writing at those speeds. Actual speeds will be based on the host and destination devices (resorting to the lowest speed) as well as the capabilities of the USB cable being used (which we’ll dive into shortly).
The power capabilities of USB 3.2 and beyond
Even early versions of the USB standard were designed to power connected peripherals. USB 2.0 delivered 5V at 500 mA, for a total power output of 2.5 watts. As the technology has matured, the charging and powering capabilities of USB have also evolved. USB 3.0 ports can support other USB specifications for increased power, including the USB Battery Charging Specification for up to 1.5 A or 7.5 W. In the case of USB 3.1, the USB Power Delivery Specification was updated to charge the host device up to 100 W.
Now desktop computers, laptops, docking stations, gaming PCs and more can be powered with a full-featured USB C cable.
Power direction is not fixed so that the product with the power (host or peripheral) can provide the power. For example:
A monitor plugged into the wall can power, or charge a laptop while still displaying.
USB power bricks or chargers can supply power through any of a laptop’s USB C ports.
This updated power delivery specification is a major leap forward from earlier versions and has huge potential to unify data and power delivery standards across a wide variety of electronic devices.
USB and industrial computers
While USB Type-C and USB 3.2 are sometimes used interchangeably, they are not one in the same. Both USB Type-A and USB Type-C connectors are used to facilitate 5 Gbps and 10 Gbps (USB 3.2 Gen 1 and Gen 2) connections, and USB Type-C is also used to facilitate the 20 Gbps (USB 3.2 Gen 2×2), 40 Gbps (USB4), and 80 Gbps (USB4 V2) connections.
We expect that the majority of industrial computers will continue to feature both USB Type-A and USB Type-C connectors, as well as support for multiple data transfer speeds and power handling, for the foreseeable future. It rests on manufacturers to appropriately label USB ports going forward to help avoid confusion.
USB cable compatibility & capabilities
One final variable to consider when trying to utilize USB 3.2 or USB4 transfer rates and power output to their fullest potential is the USB cable. All three parts of the equation have to be compatible with the desired transfer and/or charging rate. That includes the source (e.g. your computer), the USB cable, and the destination device (e.g. a hard drive or other system). When using products with different USB capabilities, the data transfer speed and charging capabilities will top out at the highest capability of the lowest performing component of the three.
Cables with more wires offer more features
The additional wires in USB 3.2 cables enable ultra fast data transfer as well as the dramatic increase in power output capabilities. They also provide additional features. For example, USB 3.2 connections can also offer DisplayPort capabilities, provided the hardware and cable are compatible. This makes 4k video output, data transfer, power output, and even power input possible over a single cable. With these new capabilities, creating a new standard port (USB Type-C) means that at some point soon, the vast majority of connections could require significantly fewer cables.
Conclusion: What you need to know about USB Type-C and USB 3.1, 3.2 and USB4
The launch of the USB Type-C connector, and the evolution of USB data handling and charging standards offer some very exciting possibilities for today’s computing devices. However, they’ve also created their fair share of confusion. Here are the key takeaways:
USB Type-C is NOT the same thing as USB 3.2 or USB4
USB Type-C ONLY describes the physical connector
USB 3.2 and USB4 ONLY describes the capabilities of the port
A Type-C connector does not automatically indicate that a USB port will support 10 GBps or faster data transfer speeds.
The term “USB 3.1” or “USB 3.2” may be used to describe ports that support either 5 Gbps data transfer (USB 3.2 Gen 1) or 10 Gbps data transfer (USB 3.2 Gen 2)
The appropriate cables and compatible hardware are required to maximize the data transfer speeds, power delivery, and additional features (like 4k video)
USB 3.2 and USB4 are fully backwards compatible with previous versions, but USB Type-C is not strictly backwards compatible due to the new port form factor, although adapters are readily available
We completely agree that this is confusing! If you still have questions, or would like to chat with one of our Solution Specialists about an upcoming project involving any of the USB standards or connectors covered here, don’t hesitate to reach out.
This blog was originally posted on July 21st, 2020. It was updated for content on November 1st, 2022.
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Darek is the Communications Manager at OnLogic. His passion for both journalism and technology has led him from the newsrooms of local papers to the manufacturing floor of IBM. His background in news gathering has him always on the lookout for the latest in emerging tech and the best ways to share that information with readers. In addition to his affinity for words, Darek is a music lover, juggler and huge fan of terrible jokes.