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Depletion-mode JFETs do not share the well understood andeasy-to-drive gate characteristics of silicon mosfets and siliconIGBTs. Instead they are normally-on, need a negative gate drive to turnoff, and can benefit from positive gate bias to speed turn-on. So for all their high-voltage high-speed benefits, designers needto change their mind-set if they are to produce efficient fail-safePSUs using SiC JFETs. All SiC JFET makers are taking steps to prevent gate driveconfusion from slowing the development of their market. Two weeks ago, PI bought Swiss IGBT driver firm CT-Concept Technologie . IGBTs are the all-silicon way to switch multi-kW inductive loadssuch as industrial motors, and these are frequently bought inscrewdriver-friendly half-bridge or three-phase modules. To make a single high-power entity that receives its switchinginstructions over an optical fibre or signal wire, it has becomecommon practice to screw interface and gate-driver components tothe top of the power module in the form of a small PCB. And it is these screw-down driver PCBs that Concept makes, basedaround Concept's own custom driver asic - which is fabbed at one ofthe foundries that PI uses, said PI - so Lapis (was OKI), Epson,X-FAB, or Renesas. One of the big market hopes for SiC power devices is that they willdisplace silicon IGBTs from multi-kW power modules. And having a driver brand like Concept under its belt, alreadytrusted for use with the competing technology, will allow PI tosay: 'Fear silicon carbide not, if you are worried about designinga gate drive, you can just buy one instead'. And Concept's expertise in driving kilovolt switches will boostPI's applications support capability for those who want to designtheir own JFET drivers. SemiSouth's driver applications notes currently call-up chips fromIxys (known under the 'Clare' brand until earlier this month). However, this may soon change as Ixys is shaping up to be a competitor to PI as it also owns powersemiconductor firms - including Wiltshire-based thyristor-maker Westcode - and makes mains-voltage LED supply ICs. A note on other SiC transistors Although depletion-mode JFETs are the most common form of SiC powertransistor (suppliers include SemiSouth, Infineon and Rohm), Creeis backing SiC mosfets, and Fairchild (through its acquisition ofTranSiC) is backing SiC NPN bipolars. SemiSouth also makes enhancement-mode JFETs but, so far, these donot work as well as depletion-mode JFETs. The e-commerce company in China offers quality products such as China Metal Hardware Fittings , China Dry Lamination Machine, and more. For more , please visit Film Blowing Machine today!
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