650 V SiC Schottky diodes boost efficiency and reliability in switching power converters

Vishay has introduced its third-generation family of surface-mount and through-hole SiC Schottky diodes with a breakdown-voltage rating of 650 V. Single-chip versions of the VS‑3C Schottky diodes are available with current ratings from 4 A to 20 A, and from 16 A to 40 A for dual-chip diodes in a common-cathode configuration.

SiC-based Schottky diodes are intended for use in high-performance ac-dc and dc-dc converter circuits, suitable applications include power factor correction (PFC) and output rectification in ultra high-frequency dc-dc converters. 

SiC diodes offer better reverse-recovery behavior and higher peak repetitive reverse-voltage capability than silicon-based diodes. SiC diodes from Vishay also benefit from an attractive product of capacitive charge and forward voltage, which helps to reduce turn-on stress and hence switching losses in the active switch. This characteristic enables increases in switching frequency and thus in power density. 

The Vishay SiC Schottky diodes feature a special structure, the backside is thinned by laser annealing, which reduces the forward voltage drop. The diodes have low typical reverse leakage current which reduces conduction losses, ensuring high system efficiency when supplying light loads. 

Unlike ultrafast diodes, the third-generation SiC Schottky diodes have almost no recovery tail, which further improves efficiency. The reverse recovery times are nearly temperature-independent, enabling operation at higher temperatures up to 175 °C without shifts in power efficiency caused by switching losses. 

The VS-3C 650 V diodes are notable for high reliability, illustrated by the stringent testing performed by Vishay: higher-temperature reverse bias testing lasting 2,000 hours, and temperature cycling testing for 2,000 cycles.