GaN Talk Blog

Dear Friends, colleagues and partners of EPC,

Happy New Year to you and your family from all of us at EPC!

2019 was a year to remember for EPC’s GaN innovations and the multiple use cases for GaN that have come to fruition. EPC’s latest generation of GaN products have enabled engineers to gain power stage advantages due to their low R_DS(on) characteristics, higher efficiency, enhanced thermal properties, small size and low cost. Now, more than ever, power system designers are switching from silicon devices to higher performance GaN components.

This post was originally published by Dr. John Glaser & Dr. David Reusch on June 13, 2016 on the Power Systems Design web site.

Comparing Dead-time Losses for eGaN FETs and Silicon MOSFETs in Synchronous Rectifiers

There have been several comparisons of eGaN FETs with silicon MOSFETs in a variety of applications, including hard-switched, soft-switched, and high-frequency power conversion. These studies have shown that eGaN FETs have large efficiency and power density advantages over silicon MOSFETs. Here we’ll focus on the use of eGaN FETs in synchronous rectifier (SR) applications and the importance of dead-time management. We show that eGaN FETs can dramatically reduce loss due to dead-time in synchronous rectifiers above and beyond the benefits of low R_DS(on)and charge.

Silicon has been around long enough. It’s time for a younger and far more fit challenger to take over semiconductor material dominance.

When I first started developing power devices 44 years ago, the “king of the hill” was the silicon power bipolar transistor.  In 1978 International Rectifier (IRF) launched power MOSFETs as a faster alternative to the slower and aging bipolar devices.  The early adopters of the power MOSFET were applications where the bipolar just was not fast enough.  The signature example for its adoption was the switching power supply for the desktop computer; first at Apple, and then at IBM. 

With advancements in motor technology, power densities have increased; motors are built in smaller form factors and designed for higher speeds, and higher precision, which requires higher electrical frequencies.

3-phase brushless DC (BLDC) motors are compact for their power ratings, can be precisely controlled, offer high electro-mechanical efficiency, and can operate with minimal vibration when properly controlled. These motors are increasingly or exclusively used in precision applications like servo drives, robotics, such as surgical robots, and drones, such as quadcopters. To keep current ripple within a reasonable range, these motors – given their low inductance – require switching frequencies up to 100kHz. A FET that can operate efficiently at high frequency is required to minimize losses and offset the torque ripple in the motor which creates vibrations, reduces drive precision and decreases efficiency.

This post was originally published by M. Di Paolo Emilio on the Power Electronic News web site.

Power switching devices based on gallium nitride technology (GaN) are in volume production now and delivering high efficiency and power density in real-world power applications. This article will examine how to implement high-power solutions with GaN technology, presenting application examples that demonstrate how GaN devices can effectively work even beyond 600 volts.

GaN devices differ from best-in-class field-effect transistors (FETs) and other silicon-based components in several important respects. GaN devices enable solutions that increase power density by two or more times over silicon-based approaches. As a result, component and package size can be reduced, yielding a solution with a smaller PCB footprint. GaN devices also offer higher efficiency than their silicon predecessors, albeit at a comparably higher overall system cost.

eGaN® FET-based power conversion systems offer higher efficiency, increased power density, and lower overall system cost than Si-based alternatives. These advantageous characteristics have spurred the presence of an ever increasing ecosystem of power electronics components such as gate drivers, controllers, and passive components that specifically enhance eGaN FET performance. Some examples of eGaN FETs are shown in figure 1.

The latest generation of 100 V GaN devices increase the efficiency, shrink the size, and reduce system cost for 48 V power conversion. The EPC2045, shown in figure 1, is rated at 100 V with 7 mΩ on- resistance that can carry a continuous current of 16 A. The EPC2045 is nearly one-tenth the footprint of a comparable Si MOSFET and has lower parasitic capacitances and can switch much faster than equivalent silicon devices, yielding lower switching loss even at higher switching frequency.

The EPC2053, shown in figure 2, is rated at 100 V with 4 mΩ on-resistance that can carry a continuous current of 32 A. The EPC2053 has lower parasitic capacitances and on-resistance than its silicon counterparts, yielding faster switching speed and lower power losses even at higher switching frequencies. These characteristics enable increasing the output power while shrinking the volume of the converter.

Motivation

The rapid expansion of the computing and telecommunication market is demanding an ever more compact, efficient and high power density solution for intermediate bus converters. The LLC resonant converter is a remarkable candidate to provide a high power density and high-efficiency solution. eGaN^® FETs with their ultra-low on-resistance and parasitic capacitances, benefit LLC resonant converters by significant loss reduction that is challenging when using Si MOSFETs. A 48 V to 12 V, 900 W, 1 MHz LLC DC to DC transformer (DCX) converter employing eGaN FETs such as EPC2053 and EPC2024 is demonstrated, yielding a peak efficiency of 98.4% and a power density exceeding 1500 W/in³.

The rapid expansion of the computing and telecommunication market is demanding an ever more compact, efficient and high power density solution for intermediate bus converters. The LLC resonant converter is a remarkable candidate to provide a high power density and high efficiency solution. eGaN® FETs with their ultra-low on-resistance and parasitic capacitances, benefit LLC resonant converters by significant loss reduction that is challenging when using Si MOSFETs. A 48 V to 6 V, 900 W, 1 MHz LLC DC to DC transformer (DCX) converter employing eGaN FETs such as EPC2053 and EPC2023 is demonstrated, yielding a peak efficiency of 98.1% with a specific power of 48 W/cm2 (308 W/in2) and power density of 69 W/cm3 (1133 W/in3).

As the new year starts, it is worth spending a few minutes to review the successes of 2018 and look ahead to expectations for 2019. 

Over the past year, the applications taking advantage of GaN’s superior performance continued to expand and the knowledge base of GaN users continued to broaden.  The world has seen in operation the autonomous vehicles that GaN enables. Digital communications have been vastly improved with the use of GaN FETs and ICs in high speed, energy saving envelope tracking power supplies. The dream of a wireless world is coming closer to reality with the emergence of large surface area wireless power.