Putting GaN to Work in Your Power Supply

The 2012 Darnell’s Power Forum will start with a half-day, pre-conference seminar on Tuesday, September 18th on "Putting GaN to Work in Your Power Supply" to be presented by Robert V. White, Chief Engineer at Embedded Power Labs and a widely recognized expert in power systems architecture and digital power management. Gallium nitride (GaN) based power switching devices are now available from multiple suppliers. These devices offer much faster and lower loss switching than today’s silicon MOSFETs – and promise smaller and more efficient power supplies and dc-dc converters. Just as power supply engineers 30 years ago had to learn new techniques to use the newly introduced MOSFETs, today’s engineers will have to learn some new techniques to put GaN devices to work in their designs.

This seminar starts with a comparison of the material properties of silicon, silicon carbide, and gallium nitride. How the material properties relate to the electrical device properties is explained. Next is a description of the structure and basic operating principal of GaN switching devices. Then key specifications of GaN switches and silicon MOSFETs with similar voltage and current specifications are compared.

With an understanding of the GaN switches, the discussion moves on to explore the circuit techniques needed to drive the gates of both depletion mode and enhancement mode GaN devices are shown. The implications of switching with nanosecond rise and fall times are discussed, with special attention given to the importance of minimizing the common source inductance is discussed. Some problems with making accurate measurements are briefly discussed.

The seminar then shows examples of a 48 to 1.2V buck converter and a dual active bridge isolated dc-dc converter using GaN devices, including experimental data. The advantages and disadvantages of GaN devices in each are discussed. The last section of the seminar addresses the application issues of paralleling GaN devices, PCB layout, and thermal management.

You can find the complete outline for this in-depth three-and-a-half-hour engineering seminar here.