SLUAAC5 August 2021 UCC28700 , UCC28701 , UCC28702 , UCC28703 , UCC28704 , UCC28710 , UCC28711 , UCC28712 , UCC28713 , UCC28720 , UCC28722 , UCC28730 , UCC28740 , UCC28742 , UCC28910 , UCC28911
Remember when designing a DCM flyback controller that uses the transformer aux winding for fault sensing to sample the input and output voltage. It is critical that the aux winding waveform is as clean as possible with as little ringing on it as possible. Some designers struggle with this ringing caused by parasitic inductances and capacitances that cause false OVP or UVLO faults. This application note describes how to prevent false OVP and UVLO faults, A RCD clamp and or a snubber across the flyback converter’s output rectifier is recommended to dampen the aux winding ringing.