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UCC28740: Jitter Function and Influence for EMI Optimization

Rebecca Li
Prodigy 490 points
Part Number: UCC28740

Hi Team,

For the jitter application of UCC28740, could your help with the following 2 questions?

1. When applying jitter frequency to improve EMI, comparing with non-jitter status, will the load regulationof the non-feedback circuit drop in the flyback circuit? More importantly, will the voltage of the non-feedback circuit in light load state go much higher?

2, In order to verify the visual effects of the jitter and non-jitter on load regulation rate, is there any additional circuits are recommended to add to disable the jitter function?

Thanks,

Rebecca

  • 0
    TI__Expert 7080 points

    Hi Rebecca,

    First, Jitter will not impact the output regulation, and jitter is disabled in light load when Ifb current higher than 14.6uA.

    Second, as mentioned in above ,  The boundary of enable and disable jitter is Ifb current equal to 14.6uA. It's hard to measure the FB current. but you can test the switching frequency at ~30khz and 32khz to identify  the controller is running at FM mode or AM mode . while the power level is not too much difference around Ifb =14.6uA, shown in below control law.