The battle for wired connectors on smartphones is over, and USB-C is the way forward. This versatile port can do just about anything. It can also charge devices, transfer data, handle audio and video output, and connect accessories.
how did we get here For years, the European Union has persuaded electronics manufacturers to settle on common standards to avoid the confusion (and waste) that proprietary connectors create. In the early days, microUSB was the connector of choice, but with the advent of USB Type C, or USB-C for short, the industry moved to a new standard.
And thanks to EU regulations coming into force at the end of 2024, USB-C is essentially mandatory for all portable electronic devices (with the exception of the smallest devices like smartwatches).
Most smartphone makers quickly adopted USB-C, just as they adopted microUSB before. One big resistance is Apple, which still uses Lightning in its iPhones, AirPods, and EarPods. That’s all. Everything else has moved to USB-C, including the new Apple TV remote.
I think Apple’s lineup is a good example of why USB-C is great. Lighting is basically a USB 2.0 port. This means slow data transfer when syncing files between iPhone and computer, or moving RAW photos from memory card to iPad.
Did you know that there actually are Lightning-based card readers that work at USB 3.0 speeds? It supports it. Yet Apple never released a video adapter above 1080p.
Lightning is also limited in the amount of power it can carry. While chargers for iPhones top out at 30W, his Apple’s USB-C charger for the new MacBook can output 140W. Ok, it’s not exactly standard, but it’s not even the maximum that USB-C can carry.
Let’s sort things out and break down the main features of USB-C one by one.
data
USB was born as a data port. USB 1.0 and 1.1 were very slow and hardly remembered now, but USB 2.0 is still very active. USB-C has a total of 24 pins, 12 on each side (well, 22 pins, but let’s not get bogged down in details). There is a single D+/D- pair in the middle, which is the data connection for common USB 2.0 cables and mandatory for USB-C. This ensures that all cables have at least some degree of connectivity.
USB Type C Cable Pinout
USB 3 added a pair of cables for data transfer. There are four additional pairs of USB-C plugs. USB 2 is limited to 480MBps, but additional cabling of USB-C cables allows transfer speeds of 10, 20, 40 and even 80GBps.
A quick note: The USB-C connector is used for USB, of course, but it’s also used for Thunderbolt. Since USB 4 is based on Thunderbolt 3 and the new USB 4 version 2 is based on Thunderbolt 4, this distinction disappears.
Another interesting application is to carry PCI-Express signals. This is basically the wired version of the PCIe slot on your computer’s motherboard. Now you can connect an external GPU to your laptop using a single cable.
video
Another popular use for USB-C is video output. DisplayPort is probably the most popular use, USB-C has replaced the big old DP port. More importantly, it’s not data or video, it’s data and video and power.
This allows you to connect a single device to the hub and add a standard HDMI port, multiple USB Type A and Type C ports, perhaps a card reader, audio and mic jacks, and more. Such hubs are built into some monitors and can be activated. Plug in just one cable for a complete desktop experience.
Of course, this is very convenient for laptops, but some smartphone manufacturers offer desktop mode. So are Samsung’s DeX, Motorola’s Ready For, and Huawei. Even Apple has a Stage Manager for the iPad Pro (with USB-C of course).
There are other options besides DisplayPort, and MHL and HDMI adapters are also available. Some of these are active adapters that convert from one standard to another, but there are also simple passive adapters.
audio
A brief description of audio here. USB can power an external DAC to which headphones can be connected. However, similar to video output, there is also a passive option – audio adapter accessory mode.
USB-C has a large number of pins, some of which can be remapped to the cable required for a typical TRRS jack, so a simple passive adapter can connect the headset to the microphone. Note that this is a pure analog mode, the digital circuits are disconnected to avoid noise.
Power
The basic USB standard has a fairly low power limit (500mAh for USB 2.0), but most manufacturers don’t follow the standard closely, so 10W adapters are fairly common.
Of course, manufacturers want their products to stand out, and fast charging is one way to do that, especially now that smartphone battery capacities have reached numbers of 3-6,000mAh. This has led to many unique solutions such as Qualcomm’s Quick Charge and Oppo’s VOOC.
However, the standard method is USB Power Delivery, or USB-PD for short. The first version specified several voltage and current levels that could be supported. 2A at 5V and 3A or 5A at 12V or 20V. This gives Power Delivery a fairly wide range from 10W to 100W.
However, these fixed voltages require DC-to-DC conversion within the phone to step down to a voltage more suitable for the internal lithium battery. USB-PD Revision 2 introduced some more voltages (9V and 15V), but they weren’t enough.
Revision 3 allows the device to communicate with the charger and request a specific voltage. It can be dialed in precisely in 20mV steps from a minimum of 3.3V to a maximum of 21V. Chargers that support this are marked “Programmable Power Supply”. As such, the charger is the one dealing with the extra heat, not the phone (lithium batteries don’t like it when it gets hot).
| side | fixed source | programmable power supply |
| Constant voltage mode | 5V 9V 15V 20V |
5V program (3.3V to 5.9V) 9V program (3.3V to 11.0V) 15V program (3.3V to 16.0V) 20V program (3.3V to 21.0V) |
| At the present time | Round (PDP/Voltage) to the nearest 10mA | Truncate (PDP/program voltage) to nearest 50mA |
| increment | none | 20 mV nominal |
| Current limit mode | none | Yes, nominal 50 mA steps |
| Periodic RDO during operation | No – not applicable | Yes, required for PPS operation |
| Requires robust port design | yes | yes |
The latest USB-PD Extended Power Range standard adds fixed voltages of 28V, 36V and 48V. This enables a new maximum power of 240W (48V at 5A). There is also a new adjustable voltage supply option, allowing the device to gradually adjust the voltage between 15V and 48V in 100mV steps.
Note that for safety reasons such a strong cable requires a chip called “e-marker”. This chip tells the charger and phone (or laptop, etc.) that the cable can carry extra power.
some criticism
As much as I love USB-C, I can’t pretend it’s perfect. One of our main complaints is that while it has so many features, not all devices and all cables support everything. Many of the above features are optional.
The worst part is that it’s very hard to keep track of which devices and which cables support what. The USB-IF is trying to solve the problem with new labels that clearly indicate how much data and power a particular cable can carry.
This should also fix other complaints that the naming scheme has grown into an absolute monstrosity. Did you know that USB 3.0 is no more? It’s now reliable USB 3.1 Gen 1. But that doesn’t exist anymore either. It is now USB 3.2 Gen 1.
Things got even trickier with titles like USB 3.2 Gen 2×2. Hmm. Thankfully, they’re all replaced with clearer labels: USB 5Gbps, USB 10Gbps, USB 20Gbps, and USB 40Gbps (and maybe USB 80Gbps soon, too). much better
In terms of power, there are two levels, USB 60W and USB 240W. There is no 100W label because obviously the difference between 100W and 240W cables is so small that by the time the new label comes out there will be no point in selling the 100W cable.
Conclusion
USB-C is a great feature. Charge your phone, laptop, headphones, shaver, flashlight, or anything else that has a built-in battery and fits in your backpack.
Now you can create a comfortable workspace on your desk with a monitor, keyboard, mouse, and more all working with just one cable. And considering that the latest standard can carry many times more data and power than the original specification, USB-C is probably still evolving.
Will USB-D ever come out? Probably, but not anytime soon. Will the world ditch cables and go wireless? Probably not. Not an efficient charging method. 2.4GHz Wi-Fi is already heavily congested in apartment buildings, and 5GHz is pretty congested, so the Wi-Fi Alliance is pushing for his move to the 6GHz band.
In the near future, USB-C will be the one cable that will rule them all.
