Some factors that are not commonly considered for valley-switched flyback converters will be discussed in the presentation such as: -The effect of valley switching on the switching frequency -Effects of the harmonic bands caused by valley hunting -Magnitude of the DCM ringing compared to the switching frequency harmonics A method to analyze the contribution of the DCM ringing and the switching frequency harmonics in the common mode emissions will be introduced. The analysis uses design parameters and the state of the power supply to synthesize waveforms and break down the harmonic components to get a trend of the EMI The analysis will be used to compare the composition of the common-mode conducted EMI with different operating conditions.