CoolSiC MOSFET for high voltage auxiliary power supplies

Maximising the strong physical characteristics of silicon carbide (SiC), this ensures that the new 1,700V surface-mounted devices (SMD) offer superior reliability, as well as low switching and conduction losses. The CoolSiC MOSFETs 1,700V are targeting auxiliary power supplies in three-phase conversion systems such as motor drives, renewables, charging infrastructure and HVDC systems.

Such low-power applications usually operate below 100W. In these cases, designers very often prefer a single-ended flyback topology. With the new CoolSiC MOSFETs 1,700V in SMD package, this topology is now even enabled for DC-link connected auxiliary circuits up to 1,000V _DC input voltage. High efficiency and high reliability auxiliary converters using a single-ended flyback converter can now be implemented in three-phase power conversion systems. This leads to smallest footprints and a reduced bill-of-materials.

“Trench technology of a CoolSiC MOSFET balancing performance and reliability in operation is now available for 1,700V,” said Dr Peter Friedrichs, Senior Director SiC at the Industrial Power Control Division of Infineon. “It combines the best of SiC properties: low losses with small footprint, in a high voltage SMD package. This helps our customers to significantly reduce the complexity in their auxiliary power supplies.”

The 1700 V blocking voltage eliminates design concerns regarding overvoltage margin and reliability of power supplies. CoolSiC trench technology features lowest device capacitances and gate charges for transistors of this voltage class. The result is a power loss reduction by more than 50% and 2.5% higher efficiency compared to state-of-the art 1,500V silicon MOSFETs. The efficiency is 0.6% higher, compared to other 1,700 SiC MOSFETs. The low losses enable compact SMD assembly with natural convection cooling without the need for a heatsink.

The new 1,700V CoolSiC trench MOSFETs are optimised for flyback topologies with +12V / 0 V gate-source voltage compatible with common PWM controllers. Thus, they do not need a gate driver IC and can be operated directly by the flyback controller. On-resistance ratings are 450 mΩ, 650 mΩ or 1000 mΩ. The new seven lead D²PAK SMD package offers extended creepage and clearance distances over seven millimetres. With that, it fulfills the usual 1700 V application requirements and PCB specifications, minimising isolation efforts for the design.

CoolSiC MOSFETs 1,700V in D²PAK-7L package are available and in series production.