06 Feb 2017
Trends in Power Semiconductors
Mark Patrick, Mouser Electronics, looks that the current trends that are bing seen within the power semiconductor market.
Power electronics is an area of great importance. It has been developing at a considerable rate and things which only a short time ago were not thought possible and now becmong achievable.
Power semiconductor manufacturers have been busy innovating and the result is many new standards, technologies and products.
Wide Bandgap Power Semiconductor Applications
Probably the strongest technology trend this year has been the rapid increase in availability of wide bandgap semiconductor products – those based on silicon carbide (SiC) and gallium nitride (GaN) materials.
Switches made from these materials can operate at higher switching frequencies than traditional silicon power transistors; replacing silicon MOSFETs with SiC ones in a switching power supply means it can switch three times as fast, or faster. They can also withstand higher voltages and temperatures, and can vastly reduce energy losses. In a world where almost every application is looking to improve energy efficiency, this is a particularly desirable quality.
This year, wide bandgap technologies have progressed from their very first power FET introductions in the recent past, to the demonstration of wide bandgap products in real world applications. SiC in particular has had a great year with numerous product introductions at the various power exhibitions around the world.
ST Microelectronics, one of the first companies to produce high voltage SiC MOSFETs, now has a full range of SiC devices for electric vehicles. SiC is particularly useful in this application as its efficiency means more vehicle mileage per charge, and its voltage characteristics can easily withstand the 400V used in today’s electric vehicle power trains.
With SiC, electric cars’ batteries can be charged faster and their power systems are more reliable, too. ST’s range is extensive enough to allow all the parts in an automotive power module to be converted to SiC. In terms of production, ST is currently working on 4-inch SiC wafers, but its transition to a 6-inch process should be complete by the end of this year. This move will drive down the costs of SiC production and enable the high volume production required by the automotive industry.
Figure 1: Fairchild released its first SiC product at APEC – a diode with industry-leading leakage current
This spring at APEC, Fairchild (now part of ON Semi) released its first SiC product, the FFSH40120ADN diode. This diode features extremely low and stable leakage current, which Fairchild says is the best in the industry, thanks to Fairchild’s proprietary edge termination IP. The new SiC diode is both reliable and rugged, taking advantage of the company’s advanced 6-inch SiC process to reduce substrate and epitaxy defects, combined with sealed passivation to avoid moisture ingress. The FFSH40120ADN will be used in industrial devices which require the highest possible ruggedness.
Infineon focused on SiC at PCIM this year, releasing two brand new 1200V SiC MOSFETs into its CoolSiC range. The company’s state of the art trench semiconductor process gives these parts an RDS(ON) of just 45mΩ, meaning they can operate with dynamic losses an order of magnitude lower than traditional 1200V silicon IGBTs. They feature a robust body diode with almost zero reverse recovery losses, so are ready for synchronous rectification topologies in applications like photovoltaic inverters, uninterruptible power supplies and battery charging applications.
Direct Conversion in Data Centres
Back in the spring, Google announced it was making its new data centre rack power specification available as part of the Open Compute Project. The aim of this new standard is to promote energy efficiency in data centres – these behemoths of telecoms infrastructure use a significant percentage of all the world’s power, so if their consumption could be reduced even slightly, it would still have a noticeable effect on global energy usage.
The way to do this, Google says, is to develop 48V power distribution architectures for server racks, which are much more efficient than the traditional 12V distribution systems traditionally used in this field. A big part of the energy efficiency improvement comes from the single power conversion stage specified in the standard which steps down the 48V distribution voltage to the 1V or less required at the point of load. Further gains are made by reducing losses in copper transmission components such as bus bars.
Figure 2: ST is the front runner in power management chipsets for the new 48V direct to point of load architecture for data centre server racks
Manufacturers have of course been working on their solutions for converting 48V to 1V or less in a single stage. One of the current front runners is a chipset from ST Microelectronics which enables ST’s Resonant Direct Conversion topology, a single conversion stage that turns 36 to 72Vin into 0.5 to 12Vout. Used with ST’s StripFET power MOSFETs, the circuit is more than 97% efficient (at 12V/500W).
Other power-related trends that have gained traction this year include a renewed focus on energy harvesting as part of the development of the Internet of Things (IoT). Energy harvesting is a challenging application for power electronics because it deals with tiny currents and minute amounts of energy.
Amongst the state of the art energy harvesting chips introduced this year is the ADP5091/ADP5092 power management unit for energy harvesting systems from Analog Devices, demonstrated at Embedded World. These devices are intended to charge a small Li-ion battery or super capacitor, and to power up small electronic devices from the stored energy. The power harvested can be in the range of 6µW to 600mW, and operational losses are below 1µW so very little energy is wasted. Quiescent current is 510nA during operation or 390nA during sleep mode (from SYS pin). The chips provide a 150mA regulated output between 1.5 and 3.6V.
Figure 3: TI was first to market with a 15W wireless charging power transmitter in July 2016
Also continuing to gain traction is wireless charging for mobile applications and beyond. TI won the race to release a 15W Qi-compatible wireless power transmitter; they were first to market at this higher power level, announcing in July. Their solution, the bq501210, operates at a fixed frequency which enables high system efficiency (84%) and reduced EMI. It can support several fast charging protocols along with the High-Voltage Dedicated Charging Point (HVDCP) protocol, which is used to communicate with compatible AC-DC wall adapters to adjust the input voltage. Inputs between 15 and 19V mean the full 15W can be delivered, while lower input voltages can be used to produce 5W or 10W outputs.
Developments in the world of power semiconductors this year have seen a number of innovative new products and technologies reach the market. These include, but are not limited to, GaN and SiC devices for increased efficiency at high voltages and frequencies, a new power architecture for data centres and innovation at the other end of the power scale in wireless charging and energy harvesting applications. As we move into 2017, the power industry is in as strong a position as ever to meet the calls for more efficient and more compact power circuits from the industry and consumers alike.
Products mentioned above are available from Mouser.
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About the author
Mark joined Mouser Electronics in July 2014, having previously held senior marketing roles at RS Components. Prior to RS, Mark spent 8 years at Texas Instruments in Applications Support and Technical Sales roles. He holds a first class Honours Degree in Electronic Engineering from Coventry University.
Mouser Electronics, a subsidiary of TTI, Inc., is part of Warren Buffett's Berkshire Hathaway family of companies. Mouser is an award-winning, authorized semiconductor and electronic component distributor, focused on the rapid introduction of new products and technologies to electronic design engineers and buyers. Mouser.com features more than 4 million products online from more than 500 manufacturers. Mouser publishes multiple catalogs per year providing designers with up-to-date data on the components now available for the next generation of electronic devices. Mouser ships globally to over 500,000 customers in 170 countries from its 492,000 sq. ft. state-of-the-art facility south of Dallas, Texas.
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