Issue link: https://resources.mouser.com/i/1447260
Würth Elektronik 2022 23 The SiC-MOSFET modules available feature a total gate charge of 3000nC. With an increase in the switching frequency or load power (requiring more paralleled SiC-devices with the corresponding increase of the total gate charge), 6-9W of driver system power can be expected for the most demanding present and near-future applications. Among the solutions available that meet the above specification, one of the best 6W isolated converter modules on the market has the following specification: ■ Input voltage range: 9-18V ■ Output voltage: +15V/-5V @ 6W ■ Size: 40mm x 28mm x 9mm ■ Efficiency: 76-79% ■ Parasitic coupling capacitance: 15pF ■ Weight: 12g ■ Basic insulation for V Bus : 800V Efficiency, weight, and especially the parasitic coupling capacitance are often critical parameters in high-performance systems. Especially at higher switching frequencies of the converters and the resulting very steep switching edges, the harmonics must be capacitively decoupled between the converter output stage/gate driver and the system power supply, such as from the DC-DC converter. The parasitic capacitance (C P ) between primary and secondary sides is mainly set by the interwinding capacitance of the DC/DC power transformer device. With latest SiC-MOSFETs switching at ∆U/∆t slew-rates of 100kV/us, 10pF parasitic capacitance across the barrier would cause a peak displacement current of 1A, which is coupled by the switching transistor across the isolation barrier. A high dielectric displacement current degrades the insulation barrier in the long run, disturbs the control signals, and leads to common mode currents in the corresponding device, which can be seen as typical EMC problems. ■ I P electrical displacement current ■ C P parasitic coupling capacitance It is recommended to keep C p in the auxiliary supply below 10pF. Würth Elektronik has addressed all these requirements, and it is presenting an optimized solution with its new SiC gate driver power- supply reference design. Learn More WE-XHMI Xtreme High Current Inductors Efficiency, weight, and especially the parasitic coupling capacitance are often critical parameters in high-performance systems. "