Digital Isolator Based on On-Chip Transformer for High-Voltage SiC MOSFET

In high-voltage applications utilizing Silicon Carbide (SiC) MOSFETs, digital isolators play a crucial role. These isolators separate the low-voltage control side from the high-voltage power side, ensuring the safety of both the low-voltage control circuit and operators. This paper presents a digital isolator design utilizing on-chip transformer technology, specifically designed for SiC MOSFET drivers operating at a maximum switching frequency of 100kHz. The transformer consists of two adjacent square copper windings insulated with polyimide, achieving an isolation voltage of 5kV. The proposed design incorporates pulse count techniques with a refresh module, which not only effectively reduces power consumption but also prevents error generation. Simulation results confirm the digital isolator's capability to achieve a maximum data rate of 40Mbps, a transmission delay of 21ns, and a static current of 150uA.