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ibility in the TO-247 package, for example, but for lower cost and better performance, “stacked” die arrangements are now common for high current with larger dies, especially when paralleling parts in a compact module. Solder die attach has given way to silver sintering for better thermal performance, and a DFN 8 × 8 package enables low-inductance, high- frequency layout for megahertz switching. TO-220, TO-247, and D2PAK packages are still popular, as they can allow retrofitting of SiC FETs into older designs, even those using IGBTs. Four-lead versions of these packages with a Kelvin source connection alleviate problems caused by source lead inductance interfering with the gate-drive loop.
Alongside all this, the increasing value of using SiC FETs from their electrical performance is complemented by a cost-reduction program from ongoing improvements to pro- duction yield and progress toward 8-inch wafers.
SiC FETs are a compelling solution
The ideal switch is now a little closer with the latest genera- tion of SiC FETs. Conduction and dynamic losses are the low- est ever, enabling high-frequency power-conversion stages with 99%-plus efficiency and the corresponding energy, size, and weight savings. Designers have a wider definition of “ideal”; they also want the part to be easy to drive in a convenient package, with stable characteristics, over a wide range of operating and fault conditions. At the same time, equipment end users want reliable end products with a total lifetime cost that is an improvement over older technology implementations. SiC FETs from UnitedSiC enable this with a range of parts with voltage ratings from 650 V to 1,700 V and with on-resistances down to 7 mΩ.
As a design aid, UnitedSiC’s “FET JET” calculator4 allows rapid selection and performance prediction of any of its devices in a selection of power-conversion topologies, including PFC stages and isolated/non-isolated DC/DC con- verters.
Anup Bhalla
is vice president of engineering at UnitedSiC.
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ASPENCORE GUIDE TO SILICON CARBIDE
The ideal switch is now a little closer with the latest generation of SiC FETs. Conduction and dynamic losses are the lowest ever, enabling high-frequency power-conversion stages with 99%-plus efficiency and the corresponding energy, size, and weight savings.