An optimized driver for SiC JFET-based switches delivering more than 99% efficiency

Nowadays, there is a high demand for highly efficient power converters that can be put in systems such as power factor correctors or solar panels. A silicon carbide (SiC) based power switch has a very good performance when it comes to switching and conduction losses. As on silicon, the manufacturing of junction devices is easier than MOSFET devices because the growth of highly reliable oxide is very challenging [1]. Recently, a family of high-voltage SiC junction FET (JFET) transistors has been developed which has made it possible to reach an efficiency of more than 99% with a buck converter. The low switching loss of these transistors allows for the use of a higher switching frequency and smaller external components which in turn reduce PCB area and overall system cost. A dedicated gate driver with possible bootstrap operation has been developed for a normally-on n-type JFET. It allows maximum efficiency, operation as safe as that of a normally-off switch, and reduced number of external components because of integration of voltage regulator and supervision circuitry. Bootstrapping minimizes the number of supplies needed for the power converter and reduces board space and BOM.