Using SiC JBS diode as voltage clamping in SSCB application: performances and limitations

The performances and limitation of SiC JBS diodes used as clamping devices for SSCB have been investigated trough simulation and experimental measurements. The simulations evaluations are based on CAD and electro- thermal circuit modelling of packaged devices. The simulations have been done on a wide blocking voltage range, form 80V to 1.7kV. An optimal trade-off in terms of layout and avalanche capability has been found. A failure criterion in terms of power density has been established, linked to device top metal layers melting (around 500°C) and measured on commercial devices. Avalanche to Nominal current Ratio varies between 6 up to 10 depending on the manufacturer. A LTspice electro-thermal model allows to predict the required SiC devices area to achieve specific performances. Finally, a demonstrator of 1.2kV-2x50A-SOT227 SiC JBS clamping diode is presented.