Power 101: Unlocking the Power of USB-C & Power Delivery

Intro

Hello, I'm Bruce Rose. I provide technical support for CUI, a Bel Group. CUI offers power supplies, including USB. A recent addition to USB is USB-C, which is the connector, and then USB-PD, which is a power delivery protocol.

Not All USB-C Connectors Are Created Equal

USB-C is the physical connector. All it defines is the dimensions and the construction of the connector. One of the most profound differences of a USB-C connector versus previous connectors is it can plug in either direction. There is no right and wrong that we had on USB-A and the previous connectors that you would try and plug it in, and it wouldn't work. You try it again and it'd finally work because there was a right and a wrong. USB-C there is no right and wrong. It goes in either direction. Associated with the USB-C connector, there's also many more signal lines, internal and connections, internal to the connector than were in the previous generation. And so having these more signal lines allows more advanced protocols for information and power transfer through the connector. PD is a power delivery protocol, and that defines the signals that flow through this connector in USB. In previous power delivery schemes, only five volts was to be delivered through USB. With USB-PD, we can deliver five volts. We can deliver nine volts, 12V, 15V or 20V and at different current levels up to 20 amps, which exceeds what previous connectors were able to handle and previous protocols.

USB-C and USB PD Recap

Again, to reiterate, the USB-C describes just the connector. The PD describes the signals that pass through the connector, but the truth be known, what the public is going to end up calling it really isn't material. They're all going to recognize it’s the same connector and the same signals, whether it's C or PD, and so we'll just have to see as timepasses, whether we end up calling it a USB connector, a USB-C connector, or perhaps a USB PD.

CUI Educates Customers Through Various Resources

CUI recognizes this concept of USB-C and USB-PD is new and will be confusing to a lot of people, both to developers and to customers. And so in order to help people to understand and learn more quickly, CUI has programs in place in the terms in terms of blogs, videos, whitepapers that are helping to explain what is happening with USB-C and USB-PD. CUI also recognizes that the USB-C and PD protocol are what's going to be very popular in the future, and thus we have a line of products that provide both USB-C connectors and support the PD protocol.

No Standard Exists to Identify Cables with Data Transfer Capability

When transitioning to the USB-C from what we have been doing with the previous USB-A and Mini and Micro, there are some challenges that come to pass. And that is USB-C is a higher performance and protocol, and so there's a need for cables that can support the power levels and the data interfaces. While the USB consortium has defined a method to identify cables that are appropriate for USB-C and USB-PD not everybody uses those identifying marks. And so it's up to the consumer, the user, to be able to look at their cables and understand what it is they need and what it will achieve.

USB-A is Still Relevant

USB-A has served us well in many applications. They tend to be lower power and lower data rates. Some examples are flash drives, mice, keyboards, headphones. Things like that work really well with the USB-A. However, as we move into more advanced technology monitors, telecommuting, telehealth, things like that, where we want much more power and data transfer, then USB-A is lacking, and this is where USB starts to shine. As the world and the users are transitioning from USB-A to USB-C there will still be the need for support of USB-A chargers and products, and CUI will support that need. We will be providing USB-C based power supplies and USB-A based power supplies, depending upon the need of the customer.

Capabilities and Compatibility

Another application for the USB-C connector and protocol that will become very popular is when charging devices such as cellphones, tablets, computers, laptops that they all need different voltage levels and different power levels. Previously, we had an array of connectors and chargers to be able to handle all of our different products. The advantage of USB-C is it will have the same connector and protocol that will enable the different voltage levels and the different power levels to be able to charge this array of devices.

Demo: Capability of USB-C to Negotiate Voltages and Power Levels

We're going to show the capability of USB-C to negotiate different voltages and power levels. I have my laptop computer here that’s partially charged, and I have some different USB-C power supplies that we'll use to charge laptops. And then what I have is an inline DMM, digital multimeter, to monitor the voltage and current. Make it so I can read it. I'm seeing 20.0V. Pretty wonderful. It's charging the laptop and if we look at our screen over here, the laptop is saying life is good, I'm getting a full charge. So now what I'm going to do is and I'm going to unplug the 100-watt adapter and I'm going to replace it with a 45-watt adapter. And so I plug that in and I give it a moment for the DMM to settle and the negotiations to complete. And I still see 20V. But when I look over at my screen over here, I have a message saying I can't charge at the full rate. And this is what USB-C is doing. On the first one, it negotiated not only a voltage level, but a maximum current level. On the second one it was not able to achieve the required the desired maximum current level. But it said it's good enough. And so, it's charging slowly with a smaller adapter where it was able to charge fully fast with a big adapter.

USB-IF Standards for USB PD Products

CUI USB products that employ the C connector and the PD protocol follow the compliance standards as defined by the USB consortium. In following these standards, it ensures that the user, when they take a CUI power supply and plug it in, knows that this CUI power supply will behave in a certain manner as defined by the standards, and therefore everything will be working properly.

USB-C Offers Greater Flexibility and Futureproofing

The applications for USB-C and PD are growing daily, and right now we're seeing a lot of applications that are maybe at about 100W at most, but we're soon going to be seeing applications taking advantage of the 240W level. Some examples of comparing and contrasting in the medical field. The blood pressure monitor, a portable blood pressure monitor, only needs a few watts to charge it. However, a CPAP machine that’s also a portable machine may use the full 240W. Again, we've already talked about cell phones, use fairly low power to charge, laptops use higher power to charge. We've got electric bicycles. We've got electric carts, industrial robots. All these things could use battery packs to untether them from the wall, but still need to be charged. And a USB-PD protocol works well for those applications.

Following the Demand for Higher-Power Product

The USB-C and PD standards have defined protocols for delivering up to 48V at five amps, or 240W. Today, CUI is offering power levels up to 100W. That's a very common level that is available in the industry. As more demand exists up at the higher power levels, CUI will be producing products that support those power levels. At the same time, we understand that the USB-A market still exists. We will have products still to support that market and the legacy market that needed the specific connectors, specific power levels, voltages, and currents still exist, and CUI will continue to offer products for that market.

Staying Informed with CUI Technology & Protocols

At CUI, we receive many questions regarding the USB and its technologies and protocols. We understand there's a lot of new information. Our recommendation is to think of three takeaways from this. The USB-A protocol is a legacy protocol that has served the market very well, but its limitations are five volts only, moderately low power, and reasonable data rates. USB-C has been introduced, and the USB-C itself is just the physical connector. Associated with the USB-C connector is USB-PD protocol. This protocol enables high power levels to be delivered through the USB-C connector to support the new and advanced technologies our customers are demanding. For more information, please visit our website or contact us directly. Thank you.