Is USB Type-C PD the “One Ring”?
“…one plug to rule them all
…one plug defines them
…one plug replaces all
…and with power & data binds them”
By admitting that I am a power person, I am proclaiming the height of my brow. If I resided in Middle-earth, I would not be a wizard and certainly not an Elfin Prince. Likely not even an elfin baker. Probably, I would be more like a mid-level Orc. Or, when I dream big, a Cave Troll. Unlike my designer colleagues who deal in MIPS, data rates, and state machines, I don’t have to go very broad or deep in my domain. Historically, my view of the ubiquitous USB standard and the corresponding connectors (and by default cables) in all their permutations and incarnations was “cute” and “very cute”. Data with some power thrown in to drive a few parts. Please don’t get me wrong. That does not mean it was not greatly needed and, admittedly, objectively revolutionary. From a power perspective, going back to USB 1.0, what can one really do with 5V at 100 mA? I mean it’s fine for powering a mouse but not practical in my world of digital power hogs, motors and blowers and strings of LEDs. With USB 2.0, OK—I get a half an amp. Sure. I get it. It’s a big deal. The half amp establishes USB as the mobile phone standard which gives way to the de-facto smart phone standard. (By the way…before my digital friends become too smug with the vastness of their own intelligence, I am always awed by the number of software people who look at me as if I am from Mars when I explain that wire diameter increases as the wire gauge decreases. “Dude, that’s stupid.” Whatever. I don’t make the rules I just know them.)
USB-C was released in 2014 and USB PD (Power Deliver) dates back two years prior to that. And both of those are independent of the USB revision. Standards adoption and implementation takes time. Mostly because product development takes time and when you change to a new interconnect, by definition, you are abandoning the current one. More important, you are affecting the future utility of the current user base of your device, your user base, your customers. Since the adoption of USB-C by Apple’s MacBook and Google’s Nexus Phone USB-C’s popularity is on the rise. It is now used by Asus and Nokia and it is (or will be) used by every PC docking station out there. This does not mean there are not drawbacks and potentials for confusion, but the practical functionality of being able to deliver audio, HD video, data and power via one bi-directional reversible cable will be difficult to beat.
So, getting back to the power part, historically, in the 15 years since USB was released, revisions were all about data rates—or I should say theoretical data rates—from 40 Mbps to 60Mbps, to the 10 Gbps of USB 3.1. I prefer the English vernacular description versus declaring the theoretical data rate speed; Full-Speed, Hi-Speed, Super Hi-Speed, Super Hi-Speed +! This is comparable to how I describe my involvement in personal relationships; Committed, Fully-Committed, Super-Committed and Super-Committed-All-in! With the combination of the USB-C connector, USB 3.1 and PD 1.0 you have a very functional connector cable system that can deliver almost 100 watts. That level of power can drive a lot devices. Besides IT products such as lap tops, tablets, and small printers there are many non-IT devices, of which many are part of the IOT (Internet of Things), that will significantly benefit from power and data via one standardized, reliable affordable inter-connect. Consumer devices such as low to mid-power audio and video equipment, industrial controllers and small motors often consume less than 100 watts. Medical devices such as patient monitors, CPAPs, infusion pumps and low-flow oxygen concentrators and ventilators can all run on less than 100 watts. All the advantages that USB-C brings to IT equipment can be realized, cost effectively and with minimal design effort for these devices. The main advantage comes from USB-IF increasing the level and flexibility of the power delivery capability of the standards.
I don’t want to make delivering 100 watts of DC power at 20V via a USB-C cable seem overly uncomplicated. To provide varying voltages at high current, the desired voltage and current must be negotiated over the USB power pins. That means added complexity in the USB architecture that must be integrated at the device level. Power source capabilities via USB-C PD are organized as profiles and extensions to standard profiles. Implementations of these are scarce so early adopters will have issues. However, the inter-connects are gaining popularity, design cycle by design cycle, which drives commoditization and the associated lower costs and supplier choices. The architecture is already packaged at the IC level and available, with technical support, through most large silicon providers. It has momentum and that means, in-time, it very well could be “easy” and “inexpensive” to implement. USB-C PD may well one day be the “one ring that binds them.”
