18 January 2011

Cree launches first commercial SiC power MOSFET

Cree Inc of Durham, NC, USA has introduced what is claimed to be the industry’s first fully qualified commercial silicon carbide (SiC) power MOSFET, enabling design engineers to develop high-voltage circuits with extremely fast switching speeds and ultralow switching losses.

The SiC MOSFET can be used today for solar inverters, high-voltage power supplies and power conditioning in industrial power applications. Over the next several years, SiC power switches and diodes could also expand into motor drive control, electric vehicles and wind-energy applications, says Cree. The market for power semiconductors in these applications is estimated to be about $4bn, rising to nearly $6bn by 2015.

The addition of the SiC power MOSFET to Cree’s SiC Schottky diode family enables power electronics design engineers to develop 'all-SiC' implementations of critical high-power switching circuits and systems with levels of energy efficiency, size and weight reduction that are not achievable with any commercially available silicon power devices of comparable ratings, the firm claims.

“Introduction of our SiC power MOSFET represents many years of materials research, process development and device design,” says John Palmour, co-founder & chief technology officer, Power and RF. “But the end result is that the industry’s first ‘ideal’ high-voltage switching device is no longer a future technology – it is commercially available and ready for design-in today,” he adds. Together with our 600V, 650V, 1200V and 1700V SiC Schottky diodes, Cree Power has established a new class of SiC power components that will "eventually replace silicon devices in the majority of critical power electronics applications with breakdown voltage requirements of 1200V or higher,” Palmour reckons.

“Cree’s release of the SiC MOSFET represents a major step forward in power technology and enables a new standard in performance and reliability to be reached,” comments Per Ranstad, product manager at Alstom Power — Thermal Services in Sweden. “We have been working with Cree to demonstrate the capabilities of this new device, in particular seeing its impact on energy efficiency in power systems,” he adds.

Cree’s CMF20120D SiC MOSFET provides blocking voltages up to 1200V with an on-state resistance (RDSon) of just 80mΩ at 25°C. In contrast to comparable silicon devices, the RDSon remains below 100mΩ across its entire operating temperature range. Such consistency of performance characteristics across operating conditions, along with a true MOSFET device architecture (normally-off), suits power electronics switching circuits, says the firm. Compared with commercially available silicon MOSFET or IGBT devices of similar ratings, in tests conducted by Cree the CMF20120D had the lowest gate drive energy (QG <100nC) across the recommended input voltage range. Conduction losses were minimized with forward drop (VF) of <2V at a current of 20A.

Advantages over silicon devices enable what is claimed to be unprecedented system efficiency and/or reduced system size, weight and cost through its higher-frequency operation. It can meet or beat silicon MOSFET switching speeds and reduce switching losses in many applications by up to 50%, the firm adds.

Compared with the best silicon IGBTs, the device improves system efficiency by up to 2% and operates at 2–3 times the switching frequencies. Higher component efficiency also results in lower operating temperatures. Combining these lower operating temperatures with the CMF20120D’s ultra-low leakage current (<1 micro-Amp) adds significantly to system reliability, it is reckoned.

The CMF20120D suits high-voltage applications where energy efficiency is critical. For example, in solar inverters SiC MOSFETs can be used in both the boost and inverter sections of the DC-to-AC converters. Switching losses are decreased by more than 30% using SiC MOSFETs and, when combined with Cree’s SiC junction barrier Schottky diodes, overall system efficiency has been demonstrated at >99%.

Similar efficiency benefits can be achieved in other applications that require high blocking voltages in combination with fast, efficient switching, such as industrial motor drives, high-power DC data center power architectures, PFC (power factor correction), boost and high-frequency DC/DC conversion circuits in industrial, and computing and communications power systems. In addition to potential efficiency gains, the low switching losses of Cree’s SiC MOSFETs and diodes can enable design optimization at switching frequencies up to three times those built with commercially available silicon devices, the firm claims.

“Silicon carbide technology is critical to developing the next generation of advanced, energy-efficient power electronic system designs,” explains Cengiz Balkas, Cree VP & general manager, Power and RF. “The addition of the industry’s first commercial SiC MOSFET will speed the development of smaller, faster, lighter and more efficient power devices in certain critical power device applications, with the potential to reduce global electric power consumption,” he believes. “This MOSFET is the first SiC MOSFET product that Cree plans to release, drawing on our technology and patent base.”

Cree claims that it demonstrated the first vertical SiC MOSFET devices; the first SiC MOSFETs at >600V; and the highest-voltage MOSFETs ever fabricated (10kV); as well as processing developments to enhance SiC MOS interface quality and reliability. Cree has been awarded more than 50 patents on SiC MOSFET technologies, with many patents pending.

The CMF20120D power devices are fully qualified and released for production. Samples are available from Digi-Key.

Tags: Cree SiC MOSFET

Visit: www.digi-key.com

Visit: www.cree.com/power

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