Analysis of common-mode electromagnetic interference noise in a flyback converter using a self-supply power control integrated circuit

This study analyses electromagnetic interference (EMI) noise sources generated from a new type of flyback converter which is operated from a self-supplied power control integrated circuit (IC). On the basis of analysis, a new analytical mathematical model of common-mode (CM) EMI noise path is presented. This model is easier to construct and allows researchers to better understand the impact of each parameter on CM EMI noise than former models. According to the proposed model, the capacitors from the traces connected to the ground (GND), voltage drain drain (VDD), current sense (CS) and feedback (FB) pins to the ground demonstrate the greatest impact on CM EMI. Two improved layouts are designed to verify the analysis result. The layouts were driven by the newly developed model. Test results show that they correspond with theoretical calculations supporting the analysis and the model that was developed in the course of this work.