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Wide Band Gap - The Next Generation of Power Devices

by  Llew Vaughan-Edmunds  - 07-19-2018 

Tightening industry standards and changes in government regulations are key driving factors for higher energy efficient products. For example, data centers are growing exponentially to keep up with demand. They use approximately 3% of the world’s total electricity supply (+400TWh), accounting for 2% of total greenhouse gas emissions. That is the same carbon footprint to the airline industry. With these huge demands of energy, governments are now stepping in with tighter standards and new regulations to ensure that all energy-dependent products need to be of the highest efficiency.

In parallel, we are seeing a requirement for higher power densities and smaller space. Electric vehicles are trying to reduce weight and increase efficiency, which allows for higher mileage per charge. On-board chargers and traction inverters are now using Wide Band Gap (WBG) products to achieve this.

Silicon Carbide (SiC) and Gallium Nitride (GaN) are Wide Band Gap materials that provide the basis for the next generation of power devices. Compared to silicon, SiC and GaN require 3 times higher energy to allow an electron to start move freely in the material. This results in superior characteristics and performance compared to silicon.

One of the main advantages is dramatic reduction of switching losses. Firstly this means the devices run cooler. That helps the overall system as heatsink sizes (and costs) can be reduced. Secondly, is the increase of switching speed. A designer now can go well above the physical limits of silicon MOSFETs or IGBTs. This allows the system to reduce it passive components like transformers, inductors and capacitors. Therefore a WBG solution can improve system efficiency, reduce size and component cost, whilst driving up power density.

Silicon Carbide Diodes are widely used in various PFC topologies where highest efficiency is essential. Also Electronic Reference (EMI) becomes easier to handle, due to extremely fast reverse recovery speeds. ON Semiconductor has a complete 650V and 1200V SiC Diode portfolio which covers all power ranges in single-phase and multi-phase applications. In parallel our 1200V MOSFETs will be released later in 2018 will provide highest performance with superior ruggedness and high reliability. ON Semiconductor has a patented termination structure which ensures best in class ruggedness and immunity to humidity related failures.

GaN is now becoming more accepted into the market. There has been a few iterations of the technology; from ‘D-Mode’, to Cascode, and now finally ‘E-Mode’ (normally-off) devices. GaN is a lightning-fast device which requires a lot of attention to PCB layout and optimized gate driving. We now see designers understanding how to use GaN and seeing the dramatic benefits compare to silicon. We are working with leading industrial and automotive partners to provide the highest power densities and efficiencies for next generation systems, such as power servers, travel adaptors and on-board chargers. As GaN is a very new technology, ON Semiconductor will ensure additional screening techniques and testing tailored to GaN, to provide the highest quality products in the market.

Tags:Power Supply, Networking and Telecommunications
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