A Galvanic-Free Secondary-Side Control Flyback Converter with Digital Adaptive On-Time Control and Direct Sequence Spread Spectrum Technique for 15.5% Error Recovery Rate Improvement

For today's convenient lightweight AC power adapters, the proposed galvanic-free secondary-side controlled flyback converter can reduce power modules, since the bulky pulse transformer and photo-coupler can be eliminated by using the main transformer to send the feedback control signal. The proposed direct sequence spread spectrum (DSSS) can have good encryption on the system side and improve the bit error recovery rate from 0% to 15.5%, which can tolerate large noise interference. In addition, digital adaptive on-time control is adopted to improve steady-state efficiency, with light-load and heavy-load efficiencies reaching 92% and 93.8%, respectively.