UnitedSiC released a range of SiC JFET die, suitable for co-packaging with a controller IC with built in low voltage MOSFET to fabricate an extremely fast, cascode-based, 20-100 W Flyback product. Ranging from 650 V to 1700 V, these normally-on SiC JFETs enable simplified start-up implementation with zero standby dissipation and target large Flyback AC-DC applications such as consumer adapters and auxiliary power supplies.
The normally-on JFET helps meet light and no-load dissipation regulations when coupled with a low Qg low voltage MOSFET integrated in the controller IC. SiC cascodes are extremely robust, due the inherent capability of SiC JFETs when it comes to handling repeated avalanche and short circuits. Since the SiC JFET is in series with the LV MOSFET in the control IC, the source of the normally-on JFET rises to 12 V before JFET turns off and the IC begins switching. This current path through the JFET can be used as a start-up supply for the controller IC. An auxiliary supply from the converter transformer is then gated-in when the converter starts running, with no further dissipation.
For more information, visit https://unitedsic.com.