USB-C Power Delivery: Charging, Conversion, and Emerging Applications

January 17, 2019


USB-C Power Delivery: Charging, Conversion, and Emerging Applications

With USB Type-C solutions gaining critical mass, Embedded Computing Design asks Andrew Cowell of Renesas Electronics what USB-C Power Delivery (PD) features mean for embedded engineers.

The USB Type-C specification was published in 2014, promising a significant increase in bandwidth and power delivery capability. Five years later and with USB Type-C solutions gaining critical mass, Embedded Computing Design asks Andrew Cowell, Vice President of the Battery & Optical Systems Division at Renesas Electronics Corporation, what the USB-C Power Delivery (PD) features mean for embedded engineers.

12-18 months ago, USB Type-C was all the rage. What’s the status of the technology, both from a technical and an adoption standpoint?

COWELL: Compared to the successful 20+ years of Type-A and Type-B connectors, USB Type-C offers a different class of features and performance to meet the future needs of connectivity. While the future of legacy USB technologies is uncertain, we are optimistic and continue to see healthy adoption and proliferation of USB Type-C connectors.

The adoption of the USB Type-C connection is definitely not dying down, and nothing is holding it back. The specifications supporting USB Type-C are mature and the adoption rate is solid and on track. For consumer applications, OEMs are moving as fast as they can to implement USB Type-C as their power and data connection. The penetration rate of USB Type-C within their major product lines is unprecedented.

Many computing and consumer end-equipment vendors have already adopted USB Type-C. For example, today, all of the new lines of Apple MacBook and iPad are using USB Type-C for power supply and data transfer, and many other notebook vendors are using it for at least 1-Port. Several new smartphones in the market are now using USB-C, and the power bank is another consumer product adopting USB Type-C. Additionally, in-car charging of phones, tablets, and notebooks is driving USB-C into automotive applications, too.

We expect to see widespread adoption of USB Type-C in the coming years.

Power Delivery (USB-PD), a key enhancement of USB-C, potentially opens up the technology to a much broader range of applications than before. Can you provide some insight into applications that could benefit from USB-C’s 100 W power delivery capacity?

COWELL: USB-C high-power delivery capabilities are mainly for consumer applications where USB-C technology was incubated. However, we expect to see USB Type-C go to a broader set of applications.

The USB-C standards and the USB-C ports are all about an evolutional way to interconnect with electronics devices, no matter whether the end applications are consumer or non-consumer. As long as applications demand high-speed data transfer between electronic devices through a simple-to-use connector with certain power delivery requirements, USB-C is the right choice. A good example is the automotive industry’s fast adoption of USB-C ports.

Another perspective of the future prospect of Power Delivery is the continuous explosion of battery-based devices. In addition to the previously-mentioned consumer applications like phones, tablets, and laptops, users of all battery-based devices expect certain common features:

  • Small, simple and safe connectors
  • Switchable power source/sink on a single connector
  • Faster charging
  • More efficient charging (less heat)

USB Type-C and Power Delivery are defined to meet those requirements and the USB Implementers Forum (USB-IF) has established robust compliance testing for the market to develop a safe ecosystem for 100W capabilities.

Some medical devices, such as digital microscopes with image processing features, may adopt a single USB-C port to replace the USB A port + HDMI port for a simplified design with better image transfer performance, even if full 100W isn’t required. Another USB Type-C example includes machine vision cameras for industrial applications, such as those offered by companies like Matrix Vision and Edmund Optics (Figure 1).

Figure 1. The 12.4 MP Matrox MATRIX VISION BlueFox USB3 Vision Camera is the type of industrial vision system primed to take advantage of USB-C's power delivery capabilities.

What challenges do the power delivery faculties of USB-C present in terms of charging and voltage, regulation for design engineers?

COWELL: While the USB-C port offers high-power capabilities, its wide voltage range of 5V to 20V brings challenges to battery chargers and buck-boost converters connected to it. This is because there is no definite relationship between input-to-output or output-to-input, which warrants either a buck or boost converter topology.

Renesas addressed this challenge by adopting a buck-boost topology approach and developed the industry’s first USB-C buck-boost battery charging solution, the ISL9237 introduced in early 2015. Since then, Renesas has developed the ISL9238x product family, and recently the ISL9241 product, which is the industry’s first USB-C ‘Combo’ buck-boost charger to support both Narrow Voltage Direct Charging (NVDC) and hybrid power buck-boost (HPBB).

Figure 2. Renesas' ISL9241 USB-C combo buck-boost charger supports both Narrow Voltage Direct Charging (NVDC) and hybrid power buck-boost (HPBB).

Renesas designed its buck-boost battery charger products to support USB-C power applications across the full voltage range (5V to 20V) with no dead-zone. These products offer multiple operation modes to efficiently utilize adapter and battery power, and improve overall efficiency. For example, the ISL9241 can be configured in HPBB mode for higher power applications to reduce the power loss and improve efficiency. The unique reverse turbo mode and supplemental power mode allow the system to run at its highest possible speed while prolonging battery run time. In addition to conventional protection features such as over voltage (OVP), over current (OCP), and over temperature (OTP) protection, Renesas battery charger products keep monitoring power charging/discharging and provide PROCHOT# signals for protection against battery/adapter overheating.

Another customer challenge for USB-C adoption is that designs need to be compliant with USB-C PD standards. Renesas helps customers by providing USB-C compliant solutions, which in turn reduces their development time and cost.

What are the areas of improvement for the technology, or potential USB-C innovations on the horizon?

COWELL: Renesas will continue product innovation and provide total system solutions for USB-C applications. A good example is Renesas’ development of new solutions for multiple USB-C port devices. They enable more efficient and flexible power delivery between the sources and sink devices by organically integrating Renesas’ technologies in the USB-PD controller, buck-boost battery charger, and voltage regulator.   

We also see tremendous potential for more battery and power applications to adopt USB-C and USB-PD, and use its cryptographic-based authentication. USB Type-C authentication offers an extra level of safety and security by providing a means for host systems to confirm the authenticity of a USB device or USB charger. This mitigates risks and prevents counterfeit device power sources from attempting to exploit a USB-C connection.

Renesas continues to develop best-in-class power delivery and power management solutions to support a robust, safe, and unified USB-C ecosystem, and expand into different markets. In addition to providing power delivery, USB-C is also defined as a configurable high-speed data bus, which OEMs will continue to utilize and evolve to provide a high-performance interface that suits different markets.

Andrew Cowell is Vice President of the Battery & Optical Systems Division at Renesas Electronics Corporation. Prior to his current role, Cowell served as Senior Vice President of Intersil’s Mobile Power Products and Vice President of Analog Marketing at Micrel Semiconductor. He began his career as a design engineer at Advanced Power Supplies, and  holds a First Class Honors degree in Electronics from Middlesex University in the UK.