All you need to know about USB 3.1, the USB Type-C connector, and USB Power Delivery

All you need to know about USB 3.1, the USB Type-C connector, and USB Power Delivery

Few are the technology standards as ubiquitous as Universal Serial Bus, commonly known as USB. For almost two decades, it has been doing a great job at connecting our gadgets with one another, allowing them to transfer data back and forth at fast, and sometimes really fast, speeds. But despite the standard's popularity, the general audience doesn't seem to be entirely familiar with its latest specifications. Well, we're here to rectify that. Here's all you need to know about USB 3.1, USB Type-C, and USB Power Delivery. 

USB 3.1 and USB Type-C are not the same thing


We've noticed that the terms USB 3.1 and USB Type-C are sometimes used interchangeably, which leads us to believe that the difference between the two isn't clear enough. Simply put, USB is the industry standard and 3.1 is its revision number. It is a technology, not a physical thing. Type-C, however, is just a new type of connector. It is comprised of a Type-C plug and a Type-C receptacle.

It is important to know that while USB Type-C is designed to carry USB 3.1 signals, a device employing the connector is not necessarily compliant with USB 3.1. The Nokia N1 tablet, for example, is a USB 2.0 device even though it uses the Type-C connector. Same goes for the OnePlus 2 smartphone. At the same time, it is possible for a device to use a USB 3.0 Type-A connector – that sexy blue one you find on modern laptops and desktop computers – and still be USB 3.1-compatible.

So, what's the point? Why are there devices using USB Type-C even though they're not USB 3.1-compatible? The answer is simple – convenience.

USB Type-C is reversible, durable, with a small footprint


USB Type-C is a reversible connector

USB Type-C is a reversible connector

We've all used USB cables and USB drives. We all know the frustration of it not fitting because we tried to plug it in the wrong way. USB Type-C, however, takes care of that inconvenience by being reversible. In other words, you can plug in a Type-C plug into a Type-C port either way and it will still work regardless of the type of USB connection – 3.1, 3.0, or 2.0. 

All this plugging in and out will not wear out the connector easily. Type-C is designed to endure through no less than 10,000 insertion/extraction cycles, which puts it on par with today's Micro USB connectors. No less importantly, USB Type-C is made to occupy very little space on a circuit board. This is great news for hardware designers as they'll have more precious room inside the electronic devices they build.

Type-C will dominate among USB connectors


The Type-C port on a Chromebook Pixel

The Type-C port on a Chromebook Pixel

What we went over in the previous paragraph were just some of the many advantages of USB Type-C over existing USB connectors. In addition to those, the new plug and receptacle can carry up to a USB 3.1 connection, transmit DisplayPort signals at up to 4K resolution, and handle up to 100W of electrical power, all at the same time. As long as all technical requirements are met, of course. Being the technically superior and future-proof connector that it is, USB Type-C is very likely to become dominant among USB connectors.

Some devices are already riding this wave of change. The newest Apple MacBook has a single Type-C port, which is used for charging, data transfer, and video output. Google's newest Chromebook Pixel features two of the ports, both with the same capabilities. Note that neither of the two computers needs a dedicated power connector as their batteries are charged via USB (more on that in a bit).

On the downside, the transition to USB Type-C will render the tons of existing USB cables useless as they're physically incompatible with the new connector. You can't insert a Type-A or a Micro USB plug into a Type-C receptacle. But embracing the future is better than resisting it, and we imagine a future where the superior Type-C connector dominates USB-enabled devices. 

Speaking of the new connector, here are some of the USB Type-C cables that have already been announced by accessory manufacturer Belkin. 


USB 3.1 is faster. Much faster


We've already covered USB Type-C in detail, and now it is time to focus on USB 3.1. But first, a bit of history. The standard's first commercial specification had a maximum data rate of 12 megabits per second, which was enough for users' needs at the time. But eventually, as peripherals' demand for bandwidth grew, the speed limit of USB 1.x became a clear bottleneck. USB 2.0 brought a significant increase in data rates by peaking at 480Mbps. USB 3.0 bumped the speed limit to 5 gigabits per second, and now, USB 3.1 boasts a 10Gbps maximum data rate. Real-life technical demonstrations have shown USB 3.1 reaching 7.2Gbps, which is pretty fast, no matter how you look at it.

As far as smartphones and tablets are concerned, data won't be moving quite as fast, although it won't be transferred slowly either. Let's say that you plug a USB 3.1-compatible smartphone to a USB 3.1-compatible computer. When you start copying files, data will be moving only as fast as the weakest link in the connection can handle it. That would usually be your computer's storage drive or your phone's storage chip. Under ideal conditions, you might be able to get figures in the realm of 150 to 300 megabytes per second, which is only within 30% of what USB 3.1 can handle, but still pretty fast.

All you need to know about USB 3.1, the USB Type-C connector, and USB Power Delivery

USB Power Delivery: how do 100 watts sound like?


At the time of its conception, USB was expected to be a vessel for carrying data, not power. That's why USB 1.x and USB 2.0 were capped at a humble 2.5 watts (0.5 amps at 5 volts) – enough to charge a compatible cell phone, but not always sufficient to power something bigger, such as an external hard drive. Then came USB 3.0 and bumped the output to 4.5 watts (0.9 amps at 5 volts). That's a much more acceptable figure, but today's mobile gadgets can easily take at least twice as much juice when charging up their batteries. Thankfully, the USB folks have developed something to address the situation. It is called USB Power Delivery.

USB Power Delivery co-exists with current USB 2.0, 3.0, 3.1, and USB Type-C specifications. It is a different thing, however. USB PD specifies five power delivery profiles – up to 100 watts in scale – applicable over a USB connection while data is being transferred. Technically, there's six of these profiles, but the so-called Profile 0 is "reserved" and doesn't do much at this time. So, here are the five that matter:

  • Profile 1 - 5V @ 2A, 10W (Default start-up profile)
  • Profile 2 - 12V @ 1.5A, 18W
  • Profile 3 - 12V @ 3A, 36W
  • Profile 4 - 20V @ 3A, 60W 
  • Profile 5 - 20V @ 5A, 100W

Inside a USB PD-compatible Type-C cable. 1 - USB Type-C plug; 2 - identification chip; 3 - shielding; 4 - power conductor

Inside a USB PD-compatible Type-C cable. 1 - USB Type-C plug; 2 - identification chip; 3 - shielding; 4 - power conductor

Does this mean that smartphones equipped with the USB Type-C connector and/or supporting USB 3.1 will charge at up to 100 watts? Sadly, no, and for a long list of reasons. Firstly, USB PD is a different specification, as we mentioned above, and may or may not be implemented in USB-capable devices. That's why having a USB Type-C port and/or supporting USB 3.1 doesn't make a device USB PD-compatible. Compatibility with the specification depends on a broader range of hardware requirements. No less importantly, pumping 60 or 100 watts of power into a smartphone's battery could result in a smokey explosion. And that's not a good thing.

So, what's in it for mobile devices, then? Well, we're not entirely sure at this point, but it is technically possible to see USB PD-compliant smartphones and tablets in the near future. They'll just be made to work with the profiles of lower power. It is up to their manufacturers to give them support for the USB Power Delivery specification. 

But wait! My phone/tablet has a charger that already outputs *insert a large number here* watts of power. Does my device already support USB Power Delivery? No, sorry to disappoint you. As we mentioned above, USB-PD is designed to deliver tons of power over a USB connection while data is moving back and forth. Your charger does provide USB-PD-like amounts of power, but it doesn't transmit data, which has allowed its manufacturer to circumvent the USB specification's limit of 0.5/0.9 amps of current. 

A few more things...


There's a couple more things we want you to know about USB Power Delivery. One of them is good, the other – not so much. The good news is that USB PD makes it possible for host and peripheral to switch roles in providing power to the other. In other words, it will be technically possible to charge a tablet from a laptop and vice versa. This feature would also allow smartphones to act as portable power banks for compatible mobile devices. 

As for that not-so-good news about USB Power Delivery, it is that the standard requires a so-called Full-Featured USB cable. These cables have a special chip inside them containing information about the cable, including the amount of power it can transmit. The device providing the power reads this data when connected and delivers no more watts than the cable can carry. Full-Featured USB cables are required for sending anything over 1.5 amps or 5 volts. Like it or not, these cables are extremely likely to be more expensive than your garden-variety USB ones. But chances are that USB PD-capable mobile devices would have one in the box. 

reference: USB 3.1, USB PD, and USB Type-C specifications at USB.org
Images courtesy of BelkinUSB.org

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30 Comments

1. bucky

Posts: 3764; Member since: Sep 30, 2009

I'm hoping the iPhone 6s will have USB type c even though the lightning connector is pretty good too.

2. Ruturaj

Posts: 1484; Member since: Oct 16, 2014

Most probably, yes, it will have it.

6. neela_akaash

Posts: 1239; Member since: Aug 05, 2014

Kudos to Mr. Nick T. For writing a detailed article on USB Type C. This article is really detailed, clear and impressive..

11. Nathan_ingx

Posts: 4764; Member since: Mar 07, 2012

Is it only me? I find the term "reversible" misleading. I can't find a better word for a thing that can be switched upside down but I find the word reversible doesn't fit. Nice article though!

27. StuiWooi

Posts: 91; Member since: Feb 19, 2013

Care to explain how you find it misleading? Type C connectors are the dictionary definition of reversible. google.co.uk/#q=define+reversible

28. Ruturaj

Posts: 1484; Member since: Oct 16, 2014

Reversible can mean that no difference between OTG adapaters and other OTG adapters. Also ZUK Z1 use type C and 3.1, so it's here guys.

21. vincelongman

Posts: 5554; Member since: Feb 10, 2013

My only minor complaint is that it doesn't fully get USB 3.1 right There is USB 3.1 Gen 1 and USB 3.1 Gen 2 Gen 1 is the same speeds as USB 3.0 (used in the 12" MacBook and new Chromebook Pixel) Gen 2 is the faster speeds shown here (used in very few PCs, probably will be in phones next year)

9. RajRicardo

Posts: 478; Member since: Feb 28, 2014

Not the 6S. May be 7.

22. Finalflash

Posts: 4049; Member since: Jul 23, 2013

Yea, 7 most likely, seeing as how the tech is very new right now and the last time Apple changed the connection it was on the 5 after 2 generations of devices. iPhone 2 was USB 1, 3g/s and 4/s were 2, 5/s/c and 6/+/s are lightning, and 7+ will likely be USB again. Just means more peripheral sales for Apple in the end.

14. Simona unregistered

no it won't

5. Napalm_3nema

Posts: 2236; Member since: Jun 14, 2013

Even though Apple helped develop Type C, I don't see them switching just yet. The outcry would be deafening.

17. joeboxer

Posts: 51; Member since: Feb 19, 2015

Apple already has it on their new MacBook

24. Napalm_3nema

Posts: 2236; Member since: Jun 14, 2013

I know, but asking those who bought that one MacBook to drop their MagSafe cables is a lot different than asking millions of Mac users and tens of millions of iPhone users to drop their cables. Not only that, the Lightning port is responsible for docks, battery cases, and a whole slew of accessories, and asking everyone to start switching those for an "S" refresh seems ludicrous. If they do it, I expect it will be on the 7.

8. nepalisherpa

Posts: 329; Member since: Jul 17, 2015

If iPhone is scheduled to get an USB Type-C then it will be iPhone 7, not 6S. That will give Apple a solid four years with the current connector (5, 5S, 6, and 6S). Doing so also won't piss as many customers off.

13. Simona unregistered

no it won't have it .. it will be still lightning..

29. enthasuium

Posts: 150; Member since: Nov 21, 2013

i dont see they would change it. Now they realized they did great mistake by lighting connector on iphone 5 . Its good but MAc book is using USB C, Too many cables for iproducts

3. Techist

Posts: 311; Member since: Jan 27, 2015

Very informative and clear article. Great job! Thanks!!

7. bambamboogy02

Posts: 819; Member since: Jun 23, 2012

Very informative article, and easy to follow along. Good writing Nick.

4. itsdeepak4u2000

Posts: 3718; Member since: Nov 03, 2012

Nice article Nick.

10. Subie

Posts: 2223; Member since: Aug 01, 2015

Nice tech article!

12. Simona unregistered

I already SAID this months ago that it is just BIG FAKE in smartphones.. When I sav LeTV Max unboxing and guy unboxed it and I saw there usb 2.0 micro usb to usb type c adapter .. I was like ; WWWTTFFF ?!?!? So basically there is no USB 3.1 protocol for fast speeds so no fast charge AT ALL ! It is just BIG S**T MARKETING CRAP !!! F-ooOF lying smartphone manufs. !!

16. Berzerk000

Posts: 4275; Member since: Jun 26, 2011

It's not lying. Type C is just a form factor of USB; saying a product uses Type C does not mean it's using the 3.1 standard. It's the manufacturer's choice whether to have the Type C form factor with USB 2.0, 3.0, or 3.1 standards. Most manufacturers use 2.0, because there isn't really a benefit to using 3.0 or 3.1 in smartphones. Fast charging can be implemented using the 2.0 standard, and there isn't a huge demand for faster USB data transfer in smartphones.

20. Simona unregistered

man i was bit sarcastic and i am coming from principal angle ..! it is clearly trick/gimmick.. .. plenty ppl will be thinking that it will have huge speeds and it will charge fast.. but after few ppl red this article are quietly surprised ..! it doesn't bring anything only flippable connector which is very huge compare to micro usb..it can lead to breaking port on the phone! they just didn't need to bother doing it when it is only 2.0 .. will never buy phone like that until it won't support 100% 3.1 protocol speeds.. no u cannot

15. wakecrash

Posts: 10; Member since: Dec 04, 2014

great article Nick

18. Mreveryphone

Posts: 1779; Member since: Apr 22, 2014

Learn something new everyday!!!

19. olatgf

Posts: 37; Member since: May 02, 2015

School Em Nick.

23. gustavoace

Posts: 187; Member since: Nov 13, 2012

Oddly, people relates USB type C to apple.... They are just ONE of the users, the technology aren't theirs. Just like thunderbolt ports...

25. Napalm_3nema

Posts: 2236; Member since: Jun 14, 2013

Apple had the largest engineering team on USB Type C. That still doesn't mean it is " theirs," because it was a team effort, but it is as much theirs as any other company that participated (which isn't really anything since it is an standard and belongs to no one).

26. Fellwalker

Posts: 511; Member since: Apr 04, 2014

Expect adverts to mislead, and reviews to not quite specify which variant is in a device. It will be like the ongoing TV and screen problem of HD, FHD, HR Ready ; but much much worse. The devices proclaiming "USB C" the loudest will most likely be the ones only supporting USB 2.

30. david316

Posts: 8; Member since: Sep 17, 2015

LOL,appreciated to your really pretty professional and detailed comprehensive description about the USB type C connectors and USB power delivery cable,we really know a lot and know how to properly choose a USB delivery cable.I also found a pretty useful article from blog.onu-mall.com/?cat=99 similar to your publicationand i also surprised by the huge collections of various USB cable and power bank from onu-mall.com/catalog/cable--amp--adapter---charger​/,i bought a really fashionable type-c cable from onu-mall.com/1m-baseus-sharp-series-type-c-usb-3-1​-to-3-0-data-sync-charging-cable-for-macbook--for-​google-chromebook-etc-gray.html for my iPAD

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