Some of the smartest people in the AV industry have been shouting about the virtues of USB-C for years. Now, the world has finally caught up: We are witnessing the dawn of the USB-C era. Like a lot of consumer-friendly technology standardization in recent years, we have the European Union (EU) to thank for this brave new world. In 2022, the EU Parliament ruled that many portable electronics operating with a power delivery of under 100 Watts, including all mobile devices, tablets and cameras sold in the EU, would be required to have a USB-C charging port by 2024. Laptops must follow suit by 2026.
The EU Parliament cited sustainability and consumer protection as their primary motivations: they wanted to reduce e-waste and protect consumers from needing to replace all their peripherals and chargers every time Apple rolls out a new connector. But for AV pros who have been intrigued by the potential of USB-C and maddened by its implementation, this ruling sliced through some of the format’s past problems like the sword of Damocles.
The EU rule didn’t just force companies to include a USB-C charging port: it also mandated that they couldn’t use proprietary fast charging protocols anymore. Now, all new devices that support fast charging are standardized to charge at the same speed via USB Power Delivery (USB PD). Once upon a time, just about every manufacturer had their own flavor of fast charging, and if you mixed up the cables and dongles, your device might charge at a snail’s pace — or worse, get zapped with enough unexpectedly high wattage to damage it.
Now, all USB PD-enabled cables and dongles must be interchangeable regardless of manufacturer. A chip embedded in the cable negotiates with connected devices to determine their capabilities and deliver the right wattage. Power supply is bidirectional and configurable up to 48V, 5 A, and 240w — an ample supply that can dramatically simplify cable configurations and AV setups.
So now, thanks to the EU, everything is simple: one connector, one cable, one charging protocol that you can count on to be available on practically every new portable device, peripheral, and computer. The connector itself is even less annoying than its USB-A predecessor: a fully reversible design that can’t be accidentally inserted upside down. It’s an I/O utopia.
Right?
To put it mildly, no. USB-C is powerful, but it’s not simple. Before you start throwing out all your HDMI distribution gear and filling your stockroom with USB-C cables and extenders, there are some caveats, challenges and complexities to consider. USB-C is likely to be a big part of your future designs, but if you don’t pay attention to these “gotchas,” it will be an even bigger headache.
#1 Easy Come, Easy Go
Part of HDMI’s enduring popularity as a connector is its reliability and security. By contrast, the nifty reversible USB-C connectors come loose at a sharp look. The design has excellent ease of use, but less than ideal peace of mind.
This is a surmountable problem. There are pro-quality USB-C cables with proprietary locking mechanisms, and you can also mitigate the issue with good system design. Make sure any non-stationary devices or exposed USB-C cables connect to easily accessible ports. I’d also advise you to keep cable runs short to avoid any unnecessary weight on the connector, but, well, see #2.
#2 More of a Sprinter than a Distance Runner
USB transfer modes are now capable of impressive transfer speeds. The most advanced USB transfer mode specification has a maximum nominal rate of 120 Gbps — which it can deliver over a passive cable for slightly less than one meter.
That’s a shockingly short distance that doesn’t line up with the reality of most AV applications or user experiences. You probably have at least a six-foot USB-C cable in your junk drawer right now. However, actual distance limitations always depend on the transfer mode, the use case and the cable technology. You can send power and peripheral controls over a much longer distance than you can send uncompressed 8K@60 Hz video. You can also extend USB signal range with active cables, active optical cables, or an extender.
#3 What’s in a Name?
Pop quiz: which of the following USB transfer modes is the fastest?
- USB 5Gbps
- USB 3.0 (Superspeed)
- USB 3.1 Gen 1
- USB 3.2 Gen 1X1
Just kidding: those are all different names for the same thing. I know, my head hurts too.
The USB Implementers Forum (USB-IF) is filled with brilliant engineers, but not necessarily marketing geniuses. USB 3.2 Gen 1X1, as it’s now officially known, is a particularly egregious example, but pretty much every USB transfer mode in use today has at least two names — a mode name and a “marketing name” — and some also have their own unique logos.
Any USB-C connector will slide easily into any USB-C port. That doesn’t mean it will deliver the expected signals. All USB transfer modes are backwards compatible, but the capabilities of any signal chain can never exceed its weakest link. Discovering these limitations sometimes requires digging deep into the specs. Product marketing materials frequently just say “USB,” “USB-C,” or even “USB 3.0,” which isn’t officially the name of anything anymore. You might see a USB-C port labelled as a Thunderbolt port: That could mean it’s a Thunderbolt 3 port (which supports USB 3.2 Gen 1X2 transfer mode), a USB4 port with Thunderbolt support, or a Thunderbolt 4 port. Digging into exactly what transfer mode each component supports will allow you to specify the right cables and extension technologies.
#4 Plenty of Alternatives
If you’re planning to use USB-C to send video signals, you’ll need to know not just the transfer mode, but the Alternative Modes (Alt Modes) supported by each port. As the name implies, Alt Modes are optional. As with HDMI’s many charming optional features, if every device in a chain hasn’t implemented an Alt Mode, Alt Mode signals cannot be transmitted.
Alt Modes dedicate some of the physical wires in a USB cable to the transmission of specific protocols. USB-IF’s Alt Mode partners include DisplayPort, Thunderbolt, and HDMI, among others. Crucially, the same device often has different transfer modes and Alt Modes enabled on different ports. If you’re lucky, each USB-C port will be labelled with transfer mode and Alt Mode symbols indicating its capabilities. If not, prepare to spend some time with your nose in the specs again — and clearly label everything yourself once you’ve sussed out the answers.
This may all sound like USB-C skepticism, but it’s not. I hope, instead, that it’s enough knowledge to clarify some ambiguity and protect people from over-hype. I welcome the USB-C sunrise, but as a new wave of USB-C products and accessories hits the pro AV market, I don’t want anyone to be blinded by supposed simplicity. The future is bright, but you’ve got to wear shades.
Brandon White is director of new product development, Vanco.