Attila - I certainly do not differentiate between "ferrite bead" and "single turn toroidal choke".
I think the SMT inductor manufacturers think of them in the same bucket too. what I think of as a "ferrite core for winding a multi turn inductor on", is invariably listed as a "ferrite bead" in the catalog these days. Most of my switchers run in the very low MHz and I like to have at least several hundred ohms at that frequency before a bus or wiring run. This often means ten or more turns. Tim N3QE Sent from my iPhone > On Dec 5, 2016, at 7:24 AM, Attila Kinali <[email protected]> wrote: > > On Sun, 4 Dec 2016 17:07:53 -0800 > jimlux <[email protected]> wrote: > >>> Wouldn't it be better to use a ferrite bead instead, for this application? >>> The much lower series capacitance and thus higher self-resonance frequency >>> should help damping the spurs. >>> >> sure, if you can get enough L. The other thing is that SMD inductors >> can be placed by machine, which isn't necessarily the case with ferrite >> beads (depending on how you do them). > > A BLM18 gets you into the order of 300Ω @ 100MHz, which is about > the equivalent of about 480nH. Using a lower current version gets > you into the 1kΩ @ 100MHz range (~1.6µH). Shouldn't that be enough > inductance? > > > Combined with some 10µF of capacitance and you already get ~15dB @ 1MHz > for a simple LC-lowpass. For additional filtering, add something like an > NFM18PS105 and you get good filtering up to ~100MHz. > > > Attila Kinali > -- > It is upon moral qualities that a society is ultimately founded. All > the prosperity and technological sophistication in the world is of no > use without that foundation. > -- Miss Matheson, The Diamond Age, Neil Stephenson > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
