USB Type-C and USB 3.1 Explained

USB Type-C and USB 3.1 Explained

USB Type-C and USB 3.1 Explained

USB Type-C and USB 3.1 Explained

The Universal Serial Bus 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 are about to change with the introduction of USB Type-C which, with the release of the new CL100 Mini-PC, is making its debut in the IPC world. 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 as USB Type-C and the new USB 3.1 standard make their way into the market. So what exactly is USB Type-C, and how does it improve upon its predecessors?

What Is USB Type-C?

USB Form Factors with ScaleType-C refers to the physical shape of the the newest USB connector. The USB Type-C connector shouldn’t be confused with the new USB 3.1 standard that was announced around the same time (we’ll get to that in a second).

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.

USB Type-C CableThe new 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 or 3.1.

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. In contrast, the latest USB 3.1 SuperSpeed+ standard (also known as USB 3.1 Gen 2) promises data transfer speeds of up to 10 Gigabits per second, equivalent to 10,000 Megabits or 1.25 Gigabytes!

One point of clarification that should be made at this point is that when the USB Implementers Forum, the group that oversees USB standards development, introduced USB 3.1 in July of 2013, they also announced that the earlier USB 3.0 standard (launched in 2008) would henceforth be referred to as USB 3.1 Gen 1. Unfortunately, because so many USB 3.0 products were already available, both USB 3.0 and USB 3.1 Gen 1 are commonly used to describe the 2008 standard. The defining characteristics of USB 3.0 (aka USB 3.1 Gen 1) are its 5 Gbit/s transfer rate and 4.5W power output, versus the 10 Gbit/s and up to 100W output of USB 3.1 Gen 2. As such, simply indicating that a USB port supports “USB 3.1” does not provide the full pictures of its capabilities. However, if a port is labeled as USB 3.0 (rather than 3.1) it can be assumed that data transfer speeds will top out at 5 Gbit/s.

USB 2.0 and USB 3.0 ports

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 3.0 (5 Gbit/s) many manufacturers (though notably not all) currently distinguish Type-A USB 3.0 ports with blue inserts, particularly when they appear on the same device as USB 2.0 ports. Alternatively, the USB SuperSpeed logo (seen below), or its “SS” abbreviation, may be used to identify USB 3.0 ports, particularly when all USB ports on a given device are USB 3.0 (as on the CL100).

USB 3.0 Ports with Logo

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 3.1 Gen 2 are impressive, many devices aren’t yet capable of reading or writing at 10 Gigabits per second, 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 3.1

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 3.0 and USB 3.1 support the USB Power Delivery Specification (USB PD), with USB 3.1 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, and USB 3.0 which can output 4.5W. Obviously it’s once again very important to know whether the USB port you are using, regardless of connector type, is a USB 2.0, 3.0 or 3.1 port in order to ensure that the device(s) you are hoping to power via USB will be provided with the requisite wattage.

USB Speed and Power Comparison Chart

Again, while USB Type-C and USB 3.1 are sometimes referred to interchangeably (due to their virtually simultaneous release) they are not one in the same. Both USB Type-A and USB Type-C connectors are used to facilitate USB 3.0/3.1 connections, and we expect that the majority of IPC systems will continue to feature both USB Type-A and USB Type-C connectors, and support for USB 2.0 and 3.0/3.1 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 and SuperSpeed+ logos and symbols pictured above on future devices.

Cable Compatibility & Capabilities

USB Type-C AdaptersOne final variable to consider when trying to utilize USB 3.1 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 USB 3.1, including the source (your computer), the USB cable, and the destination device (a hard drive or other system). Cables that support USB 3.1, 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

The launch of USB Type-C, and the corresponding release of USB 3.1 Gen 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 3.1.
        • USB Type-C ONLY describes the physical connector.
      • USB 3.1 ONLY describes the actual capabilities of the port.
    • A Type-C connector does not automatically indicate that a USB port will support USB 3.1 Gen 2 data transfer speeds (10 Gbit/s).
    • The term “USB 3.1” may be used to describe ports that support either 5 Gbit/s data transfer (USB 3.0/3.1 Gen 1) or 10 Gbit/s data transfer (USB 3.1 Gen 2).
    • The appropriate cables, and compatible hardware, are required to maximize the data transfer speeds, power output and additional features (like 4k video) provided by USB 3.1.
  • USB 3.1 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.

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.

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Comments (18)

  1. Jared
    May 4, 2016

    You should probably mention that USB Type-C also supports protocols other than USB such as Thunderbolt 3. In fact, I don’t know why they even called it a USB interface. It makes the whole thing a lot more confusing than it needed to be. Thanks for the article 🙂

  2. Darek Fanton
    May 5, 2016

    Thanks for the comment Jared! We considered including mention of Thunderbolt 3, but as you pointed out, the topic is already confusing enough without further muddying the waters. You’re right though, the Type-C port is being used for the new Thunderbolt 3 protocol which can support up to 40 Gbit/s transfer speeds and can even offer dual 4k monitor support over a single cable. The form factor definitely has a lot of potential. It will be interesting to see how hardware manufacturers utilize its capabilities.

  3. Andrew
    May 11, 2016

    Thanks for this it has helped me greatly. When USB3 launched many devices came out with a different form factor connector… a double ended connection like memory card readers, cameras and even phones. Where does this fit in? Cheers Andrew

  4. Darek Fanton
    May 11, 2016

    Hi Andrew, thanks for the comment, glad to hear the article helped!

    I’m not 100% sure I understand what you mean by a “double ended connection”. Would you be able to provide a link to an image of the type of connector you’re referring to? My assumption is you may be talking about an adapter or extender of some kind. In many instances card readers or cameras may include an adapter to connect a Mini or Micro USB (on the device) to a full sized Type-A or Type-C port (on the computer).

  5. Steve Kohn
    August 28, 2016

    I’ve just become aware of USB 3.1 and have now read a half dozen articles online on it.

    Yours is BY FAR the best. It’s the only one I’ll save.

    Much applause and thanks.

  6. Darek Fanton
    August 29, 2016

    Happy to hear that Steve, thanks for reading!

  7. Al
    September 5, 2016

    Also found this very informative, the comment about the blue/black color coding alone made the article worth reading. I noticed you focused on the female plug configurations. One twist, my Canon DSLR, Samsung Galaxy 5S and Western Digital external drives all use cables with a Type A at one end and a male plug with what appears to be a Micro A and Micro B joined together. Fortunately I have found that a old Micro B cable still works for data transfers and charging. Your article was highlighted on last weeks “Security Now” podcast, so you should be seeing more traffic.

  8. Darek Fanton
    September 6, 2016

    Thanks for the comment Al, we’re glad you found the article helpful. This is definitely a topic with plenty to explore, we could probably write a 12 part series on USB and not cover every nuance, so we appreciate your comment about the plug for your camera, phone and hard drive.

    The cable you’re describing is likely the USB 3.0 variant of the Micro-B connector. This port was used on devices that adopted USB 3.0 early on but wanted to include a lower profile connector than USB Type-A. These ports were most common on external hard drives and portable devices before the development of the USB Type-C port. The additional power and data handling made possible by the USB 3.0 protocol is handled by the pins of the second, rectangular connector next to the standard Micro USB-B port.

    USB 3.0 Micro-B Cable

    We did hear the mention on the Security Now podcast (a few folks here at Logic Supply are regular listeners). It was very kind of Steve to give us a shout out, we’ve definitely seen an uptick in visits to this post as a result.

    Thanks again for reading!

  9. Sufi
    November 5, 2016

    USB 3.0 micro B and the micro B variant with 10 pins both suck – they are poorly designed and in the last 2 years I have yet to find one which allows 1000 even connection-disconnection cycles, let alone the 10000 specified! I have not come across a type c connector on external ssd’s, mobile phones (other than iPhone) – hope this design flaw has been recognised and addressed in the specifications!

  10. Konstantin
    January 20, 2017

    Hi all!
    Could anyone advise a person who can develop a USB 3.1 Hub?
    If so, please send contacts to

  11. Jb
    January 21, 2017

    I can’t seem to find the answer to the following question clearly spelled out anywhere across our wondrous WWW. What I’d like to know is if USB 3.0 (aka USB 3.1 Gen 1) high quality type A cables, though branded and rated as having 5 Gbps transfer rates, are actually capable of delivering transfer rates of up to 10 Gbps when plugged into USB 3.1 Gen 2 type A ports, such as those found on the latest motherboard models? I’m referring to just the cable itself, all other factors being equal. Could this possibly be the reason we’re not seeing any USB 3.1 Gen 2 10 Gbps “type A male to type A female” cables being marketed as such, since in actuality they exist already in USB 3.0 (aka USB 3.1 Gen 1) cables, but aren’t being relabeled as such?

  12. Darek Fanton
    January 27, 2017

    This is a great question Jb. As we point out in the post, USB 2.0 and USB 3.0 cables have different wire counts so there are distinct capability differences between the two. However, when it comes to the performance of USB cables marked as 3.0 (USB 3.1 Gen 1) they will most commonly, with the exception of some low quality cables, perform to USB 3.1 Gen 2 standards, given that they don’t exceed 1m in length. Cables longer than 1m can not be guaranteed to support the 10Gbps transfer speeds that USB 3.1 Gen 2 connections enable, though they will still support the 100W power output. This length limitation is an important point and one we may consider adding to the body of the post.

    Thank you for asking!

  13. Shawn
    February 13, 2017

    I am in the market for a portable ssd hdd for my new MacBook Pro 2016 which has the USB Type C connectors for video editing. I see 2 options available which would be USB mode only or drives that support Thunderbolt or USB. Since I am using it for video editing I believe that the Tunderbolt would be the best fit. My question is: Isn’s the USB (event he newest version 3.1) only single direction communication , and the thunderbolt bi directional (read/write simultaneously)? The bi directional communication of the Thunderbolt would make a big difference when editing video footage from the portable drive, correct? Thanks for any clarification.

  14. Darek Fanton
    February 16, 2017

    Hi Shawn, thanks for your question. USB 3.0 and later devices feature bi-directional communication. Here’s a bit more from Make Use Of: “USB 3.0 introduces full duplex data transfer. Two of five lanes are reserved for transmitting data, while another pair is dedicated to receiving data, meaning that USB 3.0 can read and write data simultaneously at full speed. Previous USB specifications did not support bi-directional data transfer.”

    That said, in your particular situation you may find that the additional speed of Thunderbolt 3 (up to 40 Gbps) might still win out in the end. Ultimately the capabilities of your source device, your SSD and the cables that connect them will all need to be considered to get a full picture of the best solution for your needs.

  15. Lynnette Reese
    August 3, 2017

    CYou seem to imply that any USB Type-C, USB 3.1-compatible cable (Gen 1 or Gen 2) will automatically support USB-PD charging to 100W. Correct me if I am wrong, but I don’t think this is true; USB-PD is a separate specification from USB 3.1, and USB Type-C is just a connector specification. The separate specs are USB Type-C connectors, USB 3.1, USB-PD and USB Alternate Mode which uses part of USB-PD spec to work. Don’t you need a PHY that supports USB-PD AND USB 3.1 to have 10Gbps and 100W charging? And there are several levels of charging within USB-PD. I find USB to be very confusing now. A USB Type-C cable that has the extra 10 wires will support any Alternate Mode (Display Port, HDMI, MHP, and Thunderbolt); it’s the PHY on the host and device ends that get connected by USB-C cable that determine which alternate mode is used. It’s very, very difficult to sort the USB options out in one article; more like an eBook would do it. I skimmed your article and found it very well organized. Wrapping your brain around the whole thing at once is challenging at best. Where’s Jan Axelson when you need her? Her USB books were terrific.

  16. Lynnette Reese
    August 3, 2017

    By 10 extra wires, I meant 10 more than USB 2.0…

  17. Darek Fanton
    August 4, 2017

    Thank you for your comment Lynnette. As you pointed out, there’s very little that’s straight forward about USB these days. For example, with the recent announcement of USB 3.2 we’ll likely be revisiting this piece again to make an update once this new data transfer standard is official rolled out to hardware manufacturers (expected in the next two months or so).

    To your point about the charging capabilities, you are again correct that all parts of the equation (source hardware, cable and destination hardware) have to support the latest standards to realize their full charging potential over USB. We attempted to make that point toward the end of the piece and with this note in the conclusion “The appropriate cables, and compatible hardware, are required to maximize the data transfer speeds, power output and additional features (like 4k video) provided by USB 3.1”.

    As you mentioned, every aspect of USB could be its own multi-page topic, but we wanted to try and remain as concise as possible here and elected not to delve into USB-PD versions. For more information about USB Power Delivery, we recommend this piece from Electronic Design and this one from Texas Instruments.

  18. Dave
    October 2, 2017

    I would like to know why my Micro USB 2 port on my relatively new ASUS Tablet will not recognise a device that was USB 2 but even with adapter it will not recognise it.
    Also the new Type C port (also on my Tablet) will not recognise my devices again even with an adapter!
    Anyone can help as to why this is?
    I’ve tried removing Root Hub USB drivers and restarting to reload the drivers – updating drivers…
    I even tried connecting via the USB 2 port on the keyboard dock but it said “insufficient power to device” and i’m thinking: “if this is progress then can i go back to when USB really did work?”
    For the C port to be fully backwards compatible do i need a standard adapter or do i need an OTG adapter for my Tablet to recognise the devices?
    Any help please?

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