Flyback - Common Mode Filter question

[wwwenrico]

Hi,

I'm designing an off-line 50 W Flyback converter.

Can anybody explain me the difference between Toroidal shape and the UU common mode filters.

When one should use toroidal shape instead of UU filters?

Thanks,
Enrico Migliore

 

[ahsan_i_h]

The advantage of the toroidal shape is that due to its symmetry the amount of magnetic flux that escapes outside the core (leakage flux) is minimum, therefore it radiates less electromagnetic interference (EMI) to nearby circuits or equipment.

Ref: https://en.wikipedia.org/wiki/Toroidal_inductors_and_transformers