USB Type-C and USB 3.1/3.2 Explained
The Universal Serial Bus (USB) port is perhaps the most commonly used and easily recognizable PC connectivity standard found on modern hardware. But, as ubiquitous as the rectangular port and its corresponding data transfer standard 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, do-everything port for both commercial and industrial computers, making the dream of a universal connection standard, at least in part, a reality. But like any technological sea change, there’s plenty of room for confusion with USB Type-C and USB 3.0/3.1/3.2 standards. So what exactly is USB Type-C, and how does it improve upon its predecessors?
What Is USB Type-C?
Type-C refers to the physical shape of the the newest USB connector. (The USB Type-C connector shouldn’t be confused with the USB 3.1 or USB 3.2 standards.)
The most common and familiar USB connector shape is USB Type-A, which is currently used on the vast majority of computer equipment and peripherals, as well as other devices, including those that utilize its Mini-A and Micro-A variants (see image to the right). Gaining popularity in the mid 90’s, standard USB Type-A connectors are rectangular and have a distinct top and bottom, requiring them to be oriented properly in order to be plugged in, a much-maligned design flaw characteristic.
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.
The USB Type-C connector is smaller, oval, symmetrically shaped and reversible, meaning there is no “wrong way” to plug it in, eliminating one of the most common complaints about USB Type-A. USB Type-C is intended to supplant the other existing USB form factors and provide a future proof, fully featured option for hardware designers to standardize on. That said, while USB Type-C ports are becoming more and more common on mobile devices and consumer hardware (like Apple’s most recent Macbook), the industrial PC (IPC) market is just beginning to dabble with integrating USB Type-C connections into the latest generation of commercial devices.
Breaking Down USB Data Transfer Rates
It’s important to make the distinction between a given USB port form factor (like Type-A or Type-C) and the data transfer rates and power delivery available over that port. The standards that dictate the performance of USB are instead expressed as a numerical value, like USB 2.0. 3.1 or 3.2.
In terms of transfer rates, for perspective, the USB 1.0 specification introduced in 1996, offered a maximum data transfer rate of 12 Megabits per second (Mbps). USB 2.0 maxes out at 480Mbps. USB 3.0, 3.1 and 3.2 are a little more confusing. Let’s break it down.
USB 3.2 Gen 1 used to be called USB 3.0. It offers a transfer rate referred to as SuperSpeed 5 Gbps, which is about 10 times faster than the USB 2.0 standard.
USB 3.2 Gen 2, used to be called USB 3.1 released in July 2013. It offers the SuperSpeed 10 Gbps over the existing USB-A and USB-C connectors (twice the rate of USB 3.2 Gen 1.)
USB 3.2 Gen 2×2, released in September 2017 is available only for USB-C connectors using two-lane operation, It offers SuperSpeed 20 Gbps.
USB Implementers Forum (USB-IF), the group that oversees USB standards development, wants everyone to use its more human-friendly terms: USB 2.0 is USB Hi-Speed, and the version 3 variations are USB SuperSpeed 5Gbps, USB SuperSpeed 10Gbps and USB SuperSpeed 20Gbps. It should be noted that when these new generations were announced, many USB 3.0 and USB 3.1 products were already available. If a port is labeled as USB 3.0, it can be assumed that data transfer speeds will top out at 5 Gbps.
USB 2.0 (black inserts) and USB 3.0 (blue inserts)
Transfer speed differences are obviously very important to understand when you’re connecting devices via USB, and because of the large jump in speed capabilities between even USB 2.0 (480 Mbit/s) and USB 3.2 Gen 1 (5 Gbps and formerly called USB 3.0) many manufacturers (though notably not all) currently distinguish Type-A USB 3.2 Gen 1 ports with blue inserts, particularly when they appear on the same device as USB 2.0 ports. 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).
USB 3.0 Type-A (left) and USB 3.0 Type-C (right)
It should be noted however, that while the data transfer rates of USB 3.2 Gen 2 and Gen 2×2 are impressive, many devices aren’t yet capable of reading or writing at those speeds, and actual speeds will be based on the host and destination devices, as well as the capabilities of the USB cable being used (more on that later).
The Power Capabilities of USB 3.2
Even early versions of the USB standard were designed to power connected peripherals, and as the technology has matured the charging and powering capabilities of USB have also evolved. Both USB 3.2 Gen 1 and Gen 2 support the USB Power Delivery Specification (USB PD), with Gen 2 offering up to 20 volts of power at 5 amps for a potential total of 100 watts through supported hardware. This is a major leap forward from the previous USB 2.0 standard which was capable of providing 2.5 watts of power.
Again, while USB Type-C and USB 3.1 and USB 3.2 are sometimes referred to interchangeably, they are not one in the same. Both USB Type-A and USB Type-C connectors are used to facilitate USB 3.2 Gen 1 and Gen 2 connections, and USB C is also used to facilitate the USB 3.2 Gen 2×2 connection. We expect that the majority of IPC systems will continue to feature both USB Type-A and USB Type-C connectors, and 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, so expect to see more of the SuperSpeed logos and symbols pictured above on future devices.
Cable Compatibility & Capabilities
One final variable to consider when trying to utilize USB 3.1 and 3.2 transfer rates and power output to their fullest potential is the USB cable. In the case of data transfer, all three parts of the data equation have to be compatible with transfer rate, including the source (your computer), the USB cable, and the destination device (a hard drive or other system). For example, cables that support USB 3.2 Gen 2, and can transfer data at up to 10 Gbit/s, are constructed with between 15 and 18 wires. USB 2.0 cables on the other hand contain only 5 or 6 wires.
The additional wires in USB 3.1 cables enable ultra fast data transfer, as well as the dramatic increase in power output capabilities, but they also provide for additional features. As an example, USB 3.1 connections can also offer DisplayPort capabilities, provided the hardware and cable are compatible, making 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 cords.
Conclusion: What You Need to Know About USB Type-C and USB 3.1 and 3.2
The launch of USB Type-C, and the corresponding release of USB 3.1 Gen 2 and USB 3.2 offer some very exciting possibilities for today’s computing devices, but as you’ve read 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.
USB Type-C ONLY describes the physical connector.
USB 3.2 ONLY describes the actual capabilities of the port.
A Type-C connector does not automatically indicate that a USB port will support USB 3.2 Gen 2 or USB 3.2 Gen 2×2 data transfer speeds (10 Gbps or 20 Gbps).
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 output and additional features (like 4k video).
USB 3.2 is fully backwards compatible with previous versions. USB Type-C is not strictly backwards compatible due to the new port form factor, but adapters are readily available.
We get 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 covered here, don’t hesitate to reach out.