COVER STORY
Integrated GaN solution revolutionises power supply design
Andrew Pockson, Divisional Marketing Manager at Anglia, introduces a portfolio of gallium-nitride (GaN) products from STMicroelectronics which increase performance and greatly simplify power supply design. Using these new integrated GaN devices in charger and power adapter designs it is possible to cut 80% of the size and 70% of the weight compared to using ordinary silicon- based solutions. He also looks at topologies that they enable to better address the power needs of today’s industrial, consumer, computer and automotive markets.
Andrew Pockson, Divisional Marketing Manager at Anglia T
oday’s industrial, consumer, computer and automotive markets now require more and more sophisticated power management topologies to meet the power density and efficiency demanded by the latest generation of products, this all needs to be delivered within ever tightening time and budget constraints.
Many of these designs have traditionally adopted a switched-mode power converter system that incorporate discrete power MOSFETs and/or IGBTs as well as digital – microcontrollers, DSPs and FPGAs – or analog controllers. A new technology to enter the power market in recent years is GaN which has started a revolution in the power engineering world, GaN technology is enabling high speed, increased efficiency, and higher power density never before possible using silicon MOSFETs.
8 April 2021 Components in Electronics
World’s first integrated GaN and gate driver The new MasterGaN® product family from STMicroelectronics is the world’s first platform of integrated devices embedding a gate driver based on silicon technology along with a pair of GaN transistors into a single device. The combination brings a quantum leap in power performance by providing robust, efficient, and high-power density whilst at the same time simplifying the design of power systems. They are accelerating the creation of next-generation compact and efficient chargers and power adapters for consumer and industrial applications.
Today’s GaN market is typically served by discrete power transistors and gate driver ICs that require designers to learn how to make them work together for optimum performance. STMicroelectronics MasterGaN approach bypasses that challenge, resulting in faster time to market and assured performance, together with a smaller footprint, simplified assembly, and increased reliability using fewer components. As the first integrated GaN and gate driver solution to the market, MasterGaN is allowing the realisation of more compact, lighter, and highly reliable chargers and power supplies which require less design effort.
The Integration of the GaN transistors and gate drivers into a single device provides many benefits, it offers high efficiency due to an optimized gate drive layout, high power density and increased switching frequency due to minimal parasitic effects, in addition it helps to simplify the design with a compact single-chip solution.
Common Topologies
Firstly, let’s look at some common power topologies to see how GaN based devices can offer benefits.
A great example demonstrating the benefits of GaN devices can be seen with a typical flyback converter design. A common solution is where the flyback converter very often has a passive snubber to reduce the peak voltage on the primary FET, induced by the leakage inductance of the transformer, this is to allow the circuit to meet EMC standards.
This power dissipated in the passive snubber is essentially wasted energy, it can be calculated using the measurements of key criteria of the snubber design including, VCLAMP which is the voltage across the snubber when the primary FET is OFF, the transformer turns ratio and the transformer peak primary current.
By using GaN devices and employing an active clamp topology, instead of wasting the leakage inductance energy, the active clamp circuit can be used to improve efficiency by storing this previously wasted energy in a capacitor, then delivering it to the output later in the switching cycle.
Typical application diagram – Active clamp flyback
The area contained within the blue box represents the MasterGaN device.
Furthermore, combining TM (Quasi resonant) operation with an active clamp can completely remove the switching loss, allowing the switching frequency of an active clamp
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