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It’s 2018 and USB Type-C is still a mess


USB Type-C Power Cable

USB Type-C was billed as the solution for all our future cable needs, unifying power and data delivery with display and audio connectivity, and ushering in an age of the one-size-fits-all cable. Unfortunately for those already invested in the USB Type-C ecosystem, which is anyone who has bought a flagship phone in the past couple of years, the standard has probably failed to live up to the promises.

Even the seemingly most basic function of USB Type-C — powering devices — has become a mess of compatibility issues, conflicting proprietary standards, and a general lack of consumer information to guide purchasing decisions. The problem is that the features supported by different devices aren’t clear, yet the defining principle of the USB Type-C standard makes consumers think everything should just work.

A good example of Type-C problems

The charging example clearly demonstrates a very common frustration with the standard as it currently stands. Moving phones between different chargers, even of the same current and voltage ratings, often won’t produce the same charging speeds. Furthermore, picking a third party USB Type-C cable to replace the typically too short included cable can result in losing fast charging capabilities.

I have three different phone chargers from LG, Huawei, and Samsung. Points for guessing how many of them can fast charge a phone from a different brand. It’s a simple question with a complicated answer.

Depending on the charger and cable used, various configurations will power different devices at different speeds. Rather than relying on what the phone says it’s doing, we tracked the power actually passing through the cable to showcase that one company’s definition of fast charging differs from the other. Case in point, the V30 claims to “fast charge” with all the plugs except a PC USB 3.0 port, but its actual power draw varies widely and certainly doesn’t qualify as fast charging in some instances. The Huawei P20 only displays Super Charge capabilities with its proprietary cable and charger, but actually fast charges with everything I threw at it and is by far the most consistent. The P20 was also the only phone out of the three to make use of the faster-charging speeds available from desktop and laptop USB 3.0 ports, while the other two stick to the baseline 0.5A current from the 2.0 standard.

 Phone USB Type-C Chargers

This wide range of results is due to the even bigger range of charging options, varying in both output voltage and current. USB Type-C offers its own fast charging options, which can then be augmented by optional USB Power Delivery specifications, and then there are third-party fast charging solutions on top. Some cables don’t even support Power Delivery’s higher currents either, and it’s even rarer to find ones that support the very high power charging needed for laptops.

Yes, there are cable and power adapter labels, but very few consumers check for them, even when displayed correctly. Ultimately there’s very little consistency about the type of charging available. This becomes even less clear when products start using bi-directional charging capabilities like charging your phone from your laptop’s USB port.

There’s no way to tell if a USB Type-C/A cable supports high current charging or 3.1 data speeds just by looking at it.

More than just charging

It’s the same situation when you look at data transfer speeds. USB Type-C adapters support 2.x, 3.x, and Thunderbolt speeds for some ports, yet cables have to be specifically designed to meet higher speed requirements.

Devices are just as problematic too when it comes to support for “Alternate Modes” and non-USB protocols. These include DisplayPort, MHL, HDMI, Ethernet, and audio functionality provided over the connector, all of which rely on the connected devices and cables to support them. These are not a compulsory part of the specification, as the capabilities and needs clearly vary from device to device. A USB battery pack doesn’t need to support HDMI, for example.

The problem with this is that certain functionality that a user might expect in a product isn’t necessarily provided. Consumers may assume HDMI or Ethernet are supported over a USB Type-C port if a laptop is missing the regular ports, but that might not be the case. Even more frustratingly, functionality might only be restricted to certain Type-C ports on the device, so you might have 3 ports but only one that offers the functions you want.

USB Type-C is compatible with lots of features, but not every port supports everything.

USB Type-C makes functionality more opaque, not less. It claims to do everything, yet there’s no guarantee a product will actually work with any of these features. Product spec sheets can help out in this regard, but USB features are often omitted except for the port type. Even when more detailed information is available, making heads and tails of the various modes and jargon can be a lot of information for someone to digest when all they want is something that works.

Port shortages are a problem

This brings us nicely to the biggest problem with the reversible USB port, at least with smartphones: there’s a lack of them on devices. A single port for audio and power is already proving problematic in the handset space, with consumers reaching for dongles and hubs to sidestep the problem. However, this opens up a whole new world of compatibility problems, such as whether your hub or dongle supports the same charging method or standard for bi-directional power, or if data can still pass through to another device.

It’s a similar situation with a number of the latest laptops on the market. Ditching the power socket instantly reduces your peripheral count when powering up the device, which is particularly frustrating considering most laptops only have a couple of available ports to begin with. Users are increasingly being forced towards dongles to connect up to legacy ports that are still ubiquitous in other marketplaces.

Part of this is due to the fact that although USB Type-C has made its way to laptops, it’s still notably absent from mainstream displays and common accessories. So at the moment, all the new port has done is move some components out of the laptop and onto the other end of the cable. Not exactly a consumer-friendly move, given the prices often charged simply to regain functionality of older products.

Why the compatibility issues?

Cable compatibility, arguably the most frustrating of Type-C’s problems, stems from legacy support for slower devices and the introduction of higher speed use cases like video data. USB 2.0 features four just four-pin connectors for data and power, while 3.0 cables increased this to eight. So USB Type-C to A cables, which are commonly used for charging, can come in 2.0, 3.0, and 3.1 varieties, which affects the amount of data and power they can handle. USB Power Delivery is backward compatible and so is the best option for charging up devices using older cable types and speeds, but the prevalence of proprietary standards means consumers rarely really know what they are getting.

Cable quality, rating, and length affect the features available over a Type-C port.

Cable quality also comes into play here, as some charging standards will detect how much power a cable can handle and set the appropriate charging speed. In our earlier example, Huawei’s technology requires a 5A rating to charge at full speed. This is why some longer cables from third parties won’t offer the same speeds as the smaller ones included with your phone.

If that wasn’t complicated enough, the introduction of highspeed data and real-time video transfer has introduced new problems. Very fast signals suffer from attenuation and clock jitter when transferred over long distances, meaning data can get lost along the way. To address this issue cables can also come in passive or active varieties. Active cables include redrivers to restore the signal amplitude and prevent a loss in signal quality over long distances. So long cables used for very high data speeds (such as sending 4K 60fps video or data over Thunderbolt) require active components in them, while basic charging and data transfers can get away with a standard passive cable that’s less than two meters long.

DisplayPort, MHL, HMDI and Thunderbolt 20Gbps are supported via passive USB Type-C cables at less than two meters that carry the “trident” SuperSpeed USB logo or less than one meter for SuperSpeed+ labeled cables. Active cables will be required for further distances and you’ll have to look out for the Thunderbolt logo if you want 40Gbps speeds. Passive adapter cables to other USB types won’t support any of these modes.

USB Type-C Alternate Mode cable support

Wikipedia This table shows which Alternate Mode protocols are supported by which cable types.

Feature compatibility issues also involve the port and device in question, which can be configured for a wide selection of charging speeds, legacy standards, and alternate modes. Type-C is a more complex port than its predecessors, requiring substantially more software and hardware input to get things working correctly.

The starting point for USB Type-C products is the Power Delivery protocol. This isn’t just about charging, it’s also how the port communicates support for extra features like HDMI and DisplayPort by using the connectors additional pins. All of the Alternate Modes use the Power Delivery Structured Vendor Defined Message (VDM) to discover, configure, enter or exit these modes. The bottom line is that if your device doesn’t support Power Delivery, it won’t support any of these other features either. Unfortunately, Power Delivery circuitry is more complicated and expensive than the barebones circuity and the complexity scales up with the number of ports.

Even so, this doesn’t mean every Power Delivery port or device will support every feature. It’s up to device manufacturers to include the necessary multiplexers and other ICs alongside the Power Delivery components and regular port connections to support Ethernet, display, and other Alternate Modes. The diagram below shows just some of the different component blocks required to scale up the feature set of just a single USB Type-C port.

TI usb type-c port components

Texas Instruments Just one of the many possible configurations to support some advanced USB Type-C features.

The port circuitry only becomes more complicated when products want to route and manage multiple signals, such as video or audio, to multiple USB ports. The signal routing becomes increasingly complex and expensive so manufacturers restrict functionality to only one or two ports.

Even delivering power requires a complicated circuit with USB Type-C, in order to accommodate for the reversible connector type, the range of power options, and the choice between upward, downward, and bi-directional charging port and data options. To cut down on costs and complexity, you’ll often see multi-port devices only offer a single Power Delivery port dedicated to charging the device.

USB Type-C will remain a mess

USB Type-C’s complexity is undoubtedly its undoing. Although the idea of one cable to support everything sounds very useful, the reality has quickly become a convoluted combination of proprietary versus on-spec products, differing cable qualities and capabilities, and opaque feature support. The result is a standard that looks simple to use but quickly leads to consumer frustration as there is no clear indication why certain cables and features don’t work across devices.

At the same time, product developers are facing a similarly frustrating situation. Supporting the full range of advanced USB Type-C features is a complex engineering feat, far more so than previous USB generations. Furthermore, the increasing number of complex components and connectors is raising development costs and deployment time. The industry is still waiting on more integrated ICs to ease development, but the sheer range of options and features in the latest specification is making this difficult.

Not all USB Type-C ports or cables are equal. Unless that’s addressed, consumers are going to experience headaches.

Product developers and the USB Implementers Forum need to get on top of this situation and push the standard in a more consumer-friendly direction. Better labeling could help consumers identify which cables and products support which features — so far the naming schemes and logos have been rather unfriendly for casual glances. Mandatory cable and port coloring, as was the case with USB 3.0 ports, could help, but it kind of defeats the whole purpose of this one size fits all solution. Either way, a strictly enforced standard to help consumers get their head around compatibility will help.

Honestly, I can’t see an easy way out of the mess the standard is currently in. Hopefully, the situation will improve as the standard becomes more common in more devices, like displays and headphones. Hopefully we won’t be preparing for the switch to USB Type-D or whatever’s coming next by then.





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