Silicon carbide Schottky diodes trim power system losses

June 18, 2014 // By Graham Prophet
This week, Infineon added to its SiC device count with the 5th generation1200V thinQ! SiC Schottky diodes, that have ultra-low forward voltage even at operating temperatures, more than doubled surge current capability and excellent thermal behaviour.

The “Generation 5” SiC diodes use a new compact chip design, realised by merged pn junction engineering in the Schottky cell-field. This enables a smaller differential resistance per chip area. As a result, a reduction of the diode losses by up to 30% compared to the previous generation can be achieved; for example in a front-end boost stage for a 3-phase solar inverter operating at 20 kHz with full load.

At a junction temperature of 150°C, the typical forward voltage is only 1.7V, which is 30% less compared to the previous generation. This represents, Infineon believes, the lowest forward voltage available on the market for 1200V SiC diodes. Therefore, these SiC diodes are suited for applications operating at relatively high load such as UPS systems. System efficiency is improved even under low switching frequencies.

Depending on the diode ampere rating, a surge current capability now rated up to 14 times the nominal current ensures robust diode operation during application surge current events. This enables the elimination of a by-pass diode, thus reducing the complexity and system costs.

1200V thinQ! SiC Schottky diodes used in combination with Infineon's 1200V Highspeed3 IGBT in boost and Power Factor Correction (PFC) boost topologies brings significant benefits on system level, the company adds. Not only the losses in the diode are reduced, but also the performance of the Highspeed3 IGBT is improved due to reduced turn-on losses and lower EMI compared to solutions using conventional Si diodes.

The complete portfolio of the Generation 5 SiC diodes includes TO-247, TO-220 and DPAK packages, including a 40A diode in a TO-247 package as well as dual-configurations with common cathode enabling further space savings for interleaved topologies.