A 110/230 V AC and 15–400 V DC 0.3 W Power-Supply IC With Integrated Active Zero-Crossing Buffer

This work presents an offline power supply with fully integrated power stage in 0.18 $\mu \text{m}$ high-voltage (HV) CMOS silicon on insulator (SOI). It supports both ac–dc and dc–dc conversion from 15–400 V input down to 3.3–10 V output and is optimized for applications below 300 mW such as the Internet of Things (IoT), smart home, and e-mobility. An active zero-crossing buffer enables on-chip integration of the HV buffer capacitor. Below 150 V, constant ON-time control is based on voltage intervals, sensed by ten HV threshold-detection circuits. Above 150 V, the converter operates in the resonant mode. It achieves a superior power density of 458 mW/cm3 and 84% peak efficiency.