STMicroelectronics N.V. (STMicroelectronics) has introduced silicon carbide (SiC) diodes STPSC806D and STPSC1006D, which save the energy normally lost during switching. These diodes will be useful in converters for solar power systems, where every fractional efficiency percentage is essential. Power supplies for servers and telecom systems will also benefit from the cumulative savings of small improvement in efficiency.
These diodes can also be used in motor controllers, which are deployed in large numbers worldwide, thereby saving the environmental impact of many thousands of watts of generated energy.
Moreover, by saving the energy normally dissipated as heat by the silicon diode, the new SiC technology enables engineers to consider a lower maximum current rating for the diode. This allows smaller components to be used without sacrificing usable power. In high-power applications where heatsinks are normally used, these can also be made smaller leading to more compact power supplies delivering higher power density.
A further benefit for switched-mode power supply (SMPS) designers is that SiC diodes such as the STPSC806D and STPS1006D allow higher switching frequencies, which enable other components such as filtering capacitors and inductors to become smaller and less expensive, and consume less power.
SiC technology is able to deliver these benefits because no reverse recovery charge accumulates during the diode’s normal conduction period. When a conventional bipolar silicon diode is turned off, this charge must be dispelled by recombination between groups of charge carriers close to the diode junction. The current flowing during this recombination period is called the reverse recovery current. This undesired current, when combined with the voltage across associated semiconductor power switches, generates heat that will be dissipated by the switches. By eliminating this reverse recovery charge, SiC Schottky diodes have much lower switching losses across the board, leading to higher efficiency and lower heat dissipation.