Alpha and Omega Semiconductor Demonstrates 1200V UniSiC Stack-Cascode MOSFETs
Alpha and Omega Semiconductor Limited (AOS) and SemiSouth Laboratories jointly demonstrated UniSiC™, a 1200V, 90mΩ MOSFET in a TO262 package, to meet the growing need for energy efficient switching devices for high performance power conversion applications in the alternative energy, industrial and consumer segments. The dramatic reduction in form factor and figures-of-merit put this 1200V MOSFET device in a class by itself.
AOS continues to execute its strategy to be a full service power solution provider by extending its portfolio of AlphaMOS™ MOSFETs and AlphaIGBT, devices with the revolutionary 1200V MOSFET solution described in this brief. The UniSiC MOSFET provides unprecedented low Rdson and gate charge Qg, an excellent body diode with virtually no stored charge and a low diode forward voltage drop. The device may be used similar to a conventional MOSFET or IGBT, with standard gate drives and is engineered so it can be switched over a wide speed range – as fast as a Superjunction MOSFET, or as slow as an IGBT. The device has far superior characteristics compared to existing IGBTs, Silicon power MOSFETs or even the best competitive SiC 1200V MOSFET. Key data is summarized in Table 1 and Figure 1 shows the die sizes of a 1200V IGBT with co-packaged diode, the 1200V competitor SiC MOSFET and the AOS UniSiC stack-cascode device. The small die size shows the tremendous potential this device creates for future miniaturization of power circuits given how much it cuts conduction and switching losses.
The UniSiC device is formed by stacking a specially designed low voltage Silicon MOSFET atop a normally-on SiC JFET. The SiC JFET has excellent characteristics and is provided by SemiSouth, the leading supplier of SiC JFET technology. The low voltage MOSFET is specially engineered to allow optimal operation of the composite device with clean switching, low Rdson, gate charge and superb diode characteristics. It is intended to provide great ease of use, working with standard drive circuitry, and drastically improving circuit efficiencies over the whole range of load current.
"Using the superb characteristics of SiC JFETs for high voltage applications, and solving the switching problems that have plagued cascode devices in the past, AOS is in a position to offer the power electronics community a dream switch," said Dr. Anup Bhalla, Vice President of High-Voltage Discretes at AOS. "The devices can be used like conventional discrete IGBTs and FETs using the same gate drives, allowing the user to realize huge efficiency gains without too much re-engineering."
"We are very pleased with the introduction of this new high voltage technology, which, in partnership with SemiSouth laboratories, allows AOS to bring a truly revolutionary device to the world of power conversion," commented Dr. Mike Chang, President and CEO of AOS. "Products like these will set AOS apart as the high voltage supplier of choice, facilitating our twin goals of product diversification and rapid growth."
"SemiSouth is excited to see the performance achieved by AOS using our SiC power JFET die. First released in 2008, we have seen our JFET products gain rapid adoption in the market, and this first-ever stack-cascode demonstration from AOS really takes the performance and ease of use to the next level. We are pleased to have this relationship with AOS as a valued customer." said Dr. Jeff Casady, President and CTO of SemiSouth Laboratories.
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