Electronics > Projects, Designs, and Technical Stuff
30W offline isolated flyback and use of shield windings.
ocset:
Thanks, but pertaining to Flybacks. we agree that a non isolated flyback smps suffers less common mode noise (on its conducted EMC scan), then an isolated flyback?
(Albeit that yes, on occasions, non isolated flyback sometimes doesnt make sense)
T3sl4co1l:
If it's wired correctly, then by definition there is no common mode!
In practice, the three-terminal device (in, gnd, out) is often expanded to a full two-port, with CM and DM, where CM is due to ground loop, or because the input is AC it's the DM plus or minus.
Tim
ocset:
Thanks, as a finality on this theme, i postulate that if we "de-isolate" a 60W offline flyback SMPS LED driver, by connecting its primary and secondary grounds together with a short wire piece...then that 60W flyback SMPS led driver gives essentially no more common mode noise problem than an offline 60W buckboost led driver, which uses no transformer and just uses a single winding inductor. Do you agree?
T3sl4co1l:
No. The wire has impedance. The buck-boost is hopefully over continuous ground plane. Very different.
Tim
ocset:
Thanks, OK, but just for the sake of argument, lets now say the flyback is also over continuous ground plane...then do you now say that their conducted EMC signatures are the same?
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