Industry Article

USB Type-C Cables: The New Frontier

December 21, 2016 by Tom Holden, Total Phase

USB Type-C: the final frontier. These are the trials and tribulations of navigating this new cable.

USB Type-C: the final frontier. These are the trials and tribulations of navigating this new cable. Our mission: to explore exciting new features, to seek out new applications and to boldly go where no cable has gone before.

All kidding aside, the introduction of the Power Delivery and USB Type-C specifications with new, more capable cables has opened the consumer electronics universe to a number of tremendous opportunities.

In case you don’t already know, in late 2014, the USB Implementers Forum (USB-IF) defined the specification for the Type-C cable. Type-C is a cable that connects to both hosts and devices (now also sources and sinks), is small in size and double-sided, and transfers data as well as power. It is intended to replace the commonly used Standard-A, Micro-B, and a myriad of other proprietary cables and protocols, delivering more in a smaller footprint.


Warp Speed Ahead…

According to ABI Research, USB Type-C will be the standard for some 830 million smartphones shipped worldwide in 2021. That's a compound annual growth rate (CAGR) of 69.1% over the next five years!

Jeff Ravencraft, president of the USB-IF, in a recent presentation quoted research findings from IHS stating that by 2019, over 2 billion devices—that is, 40% of the USB market—will support USB Type-C.


That’s only a few years away. You can bet that, in the coming months, Type-C will become the de facto cable provided with most consumer electronics.


Resistance is Futile…

The Type-C cable is the most technically advanced cable available today, enabling data speeds up to 60 Gbps and power up to 100 watts. With speed and power like this, it’s no surprise that Apple announced its plans to transition to these connectors, beginning with the new MacBook Pro.

Apple isn’t the only company making the transition. Google’s Pixel C tablet and Pixel phones, HTC and LG smartphones, and laptops from Dell, HP, ASUS, Acer, LG, and Lenovo are also joining the Type-C revolution.


Where No Man Has Gone Before…

The Type-C cable brings with it a whole host of features that no other USB or proprietary cables offer. With these increased features comes increased complexity. Unlike its predecessors, the USB Type-C connector/cable includes 24 pins with up to 18 wires and a smart connector in the form of a chip/paddleboard using E-Marker technology.

The E-Marker chip is designed to fit inside cables and forms part of the power delivery mechanism for the new Type-C cables. As well as transmitting data at up to 60 Gbps, appropriate cables with E-Marker devices can deliver up to 100W of power in either direction. The Type-C connection can be used in a laptop for power, display, connectivity, and storage.


The Universal Serial Bus Type-C Cable and Connector Specification Revision 1.2, dated March 25, 2016, offers further specifications:


Notes: 1. USB BC 1.2 permits a power provider to be designed to support a level of power between 0.5 A and 1.5 A. If the USB BC 1.2 power provider does not support 1.5 A, then it is required to follow power droop requirements. A USB BC 1.2 power consumer may consume up to 1.5 A provided that the voltage does not drop below 2 V, which may occur at any level of power above 0.5 A.

But wait—the complexity continues… What about programming the E-Marker chip, measuring transfer degradation caused by length, etc.?

Most E-Marker chips are programmed using I2C, SWD, and SPI. The standard length for a passive USB 3.1 generation 1 or 2 Type-C cable is one meter, with many USB 2.0 Type-C cables available up to two meters.

We’re Breaking Up

That being said, the new technology has had its share of problems. While a cable’s design may be certified, there is currently no standard for proper testing and validation of every individual cable. Think about what could happen. A Type–C cable is designed to deliver a minimum of 60 watts of power in a variety of voltage and current configurations; the wrong combination through a weak cable becomes a photon torpedo. Even Scotty couldn’t fix that!

There are many reasons this could happen. What if, in the manufacturing process, the wires were set too close and therefore cause a short? Even worse, what if they were crossed and a high voltage appears where it is least expected? It doesn’t take much to create enough heat and a spark in that little space of a cable to start a fire. The result: Consumers are dealing with the risk of fire from damaged equipment, while developers and cable manufacturers are dealing with the risk of a messy recall and an even bigger mess of spin control to protect their brand. All this because the cable wasn’t tested on the manufacturing line.

But it’s not necessarily the manufacturer’s fault or the product developer’s fault. There is no testing standard for these new cables, mostly because legacy cables didn’t require this complex testing (if a cable failed, there little chance of harm the cable could just be replaced) and this part of the manufacturing/test process hasn’t evolved as quickly as adoption. Although there is increasing demand for testing, it has been slowed by the lack of affordable equipment for quality tests. As a result, there is a whole host of issues, ranging from poor performance to damage of internal circuitry and batteries of connected devices and, even worse, fires.

The time-honored maxim applies in this new frontier: Not all cables are created the same. While there are a number of quality USB Type-C cables on the market, there is also a fair share of substandard cables floating around. It’s clear that the USB Type-C protocol/cable is digging itself in and is here to stay.

I'm Givin’ You All She’s Got, Captain

Due to the added complexity of the Type-C cable and its ability to carry up to 100 watts, the risk of fire and liability has increased exponentially. So, why aren’t these cables being tested? Isn’t there a certification process? The fact is, earning a USB certification and the right to bear the logo only certifies the design and does not guarantee a level of manufactured product quality.

Current USB Type-C cable testing equipment is costly, time-consuming and not designed to quickly test the full breadth of Type-C functionality; as a direct consequence, many manufacturers don’t test every cable. We have already seen the results of this manufacturing practice in the form of recalls and lowered consumer confidence. Earlier this year, Android Central reported faulty assembly and inaccurate labeling of cable capabilities. In February, Apple announced a replacement program for a faulty USB-C cable that did not charge or only intermittently charged the MacBook. In August, accessory provider Anker was forced to recall its Type-C cables due to power issues.

How did this happen? Traditional cable testing approaches fall into two main categories:

  1. High-end – This method tests equipment that includes expensive oscilloscopes, custom fixtures, and high-performance electronic analyzers, costing manufacturers hundreds of thousands of dollars. While this works well for design validation, it is never suitable for high-volume use.
  2. Extremely basic – On the low end, testing methods that include simple continuity or next to no real testing at all (i.e., plug it in to see if it works) with statistical analysis can miss failures and cannot identify underperforming cables.

You can see that these testing extremes just aren’t enough to create a stable market. Not all companies will invest in what it takes to purchase, implement, and train their people on the expensive scopes. On the other end of the spectrum, simple testing to see if a cable works and using the statistical analysis of those results to determine if the cable is of quality isn’t adequate. What’s a developer or manufacturer to do?

Set Phasers to Stun

The USB-IF has done a great job of outlining the specification that certifies the design, but there is currently no oversight for the manufacturing of such a powerful little cable. A few independent hobbyists like Benson Leung and Nathan K have done substantial testing on their own as a community service. They have found a number of cables that have tested faulty. Leung’s findings were so devastating that Amazon was moved to stop selling “crappy cables”.

Live Long and Prosper

You don’t need to be an EE or an industry expert to realize that these cables pack a wallop. So, it’s no surprise that the consumer products industry is making the shift to the one cable that does it all: USB Type-C.

So, what does that mean for the developers and the manufacturers? As with many shifts in technology, we don’t know what we don’t know, and these new frontiers can often feel like exploring a new galaxy. Don’t worry, though; technology is now available to protect you from rogue cables.

Make it So!

Few manufacturers can survive a Samsung Galaxy-level product recall. Even if they do survive the first wave of revenue loss, the second wave—brought on by brand distrust—could be too large to survive.

What is needed today is equipment that will test these cables at a reasonable cost, with an easy set-up that doesn’t interrupt the current manufacturing line and doesn’t require extensive training of its labor force. Best-of-breed test equipment today can provide manufacturers with a reasonable, cost-effective way to incorporate comprehensive continuity testing that will result in quality cables. With minimal overhead and no need for highly trained personnel, software and hardware solutions today will ensure a safe and reliable product that consumers can put their confidence in. That, in turn, will accelerate and drive the adoption of USB Type-C technology – not to mention charge your device faster.

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  • G
    Gram December 31, 2016

    The charger for my MacBook produces 14.5V and 5.2V through a USB-C connection.
    How does the provision of 14.5V fit in with the specification?

    Like. Reply
    • TomatTP March 14, 2017
      Great question Gram. The USB Type-C specification allows for a a range of voltages to be output once the power contract is negotiated between the Source and the Sink. The bottom voltage is nominally 5 Volts and the top voltage is 20 Volts. Typical values used are 19.8 Volts for some Dell laptops, 14.8 Volts for Apple MacBook Pros, and all other ranges in between. The maximum current allowed is 3 Amps for a certified standard USB Type-C to Type-C cable and up to 5 Amps for a properly electronically marked Type-C to Type-C cable. The way in which the Source and Sink negotiate the power contract is via the USB Power Delivery specified communication channel. You can learn more about PD communications from watching this 3 minute video about our PD analyzer:
      Like. Reply