Thanks for comment

"splitting the wires" this is to explain that when measuring the impedance form input to output impedance it is like one wire. Nobody is splitting wires. What a relief that you do not do this.

Thanks fo feedback.

👍😊🙏Nice to read from you. Where are you at?

I am showing a DC (battery) source

Thanks

Thanks for input.

Many thanks!

There is though a discrepancy between the data sheet and the LTspice model, isn't there?

@@sambenyaakov Datasheet is max value. Simulation model uses characterized data, so typical.

@@klauskragelund8883 The difference is not just in the magnitude but in shape, especially at high frequency, And, since when the datasheets show max values in plots?

Thanks

There are many types and classes. The most famous CISPR25

Capacitance can indeed emulate the drop and this is how simulation models are built. But the physics is that the permeability decreases and this is the real reason for the drop in response at high frequency. On top of it there might be the resonances due to parasitic capacitances.

​@@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies). Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade. Another data point is this presentation by Wurth themselves on their CM chokes: see from 32 : 57 kzfaq.info/get/bejne/r7Fza7yhlauddmw.html At 33 : 20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it. Note that the part he is showing is an MnZn ferrite, not nanocrystalline. Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz. This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.

@sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies). Fig 7 shows that Z continues to rise steadily well past the frequency where XL plummets due to u' falling. So the impedance curve for the Wurth CM choke you showed is almost certainly explained by the parasitic parallel capacitor dominating above 2MHz, declining at 20dB/decade.

@@sambenyaakov YT suppressed my comment so I split it into two parts: Another data point is this presentation by Wurth themselves on their CM chokes: see from 32:57 kzfaq.info/get/bejne/r7Fza7yhlauddmw.html At 33:20 he states "..where the impedance drops due to the capacitance effect". Ok he could have got it wrong or was avoiding the complexities of permeability variance with frequency but I doubt it. Finally why isn't the leakage inductance impedance similarly affected by the collapse in u' after 2MHz? It continues to rise linearly, well past 2MHz. This doesn't detract from the points you were making about the properties of ferrites which encouraged me to look into far more than I expected.

@@sambenyaakov YT make it incredibly difficult to comment - this is my third attempt splitting up my reply: @sambenyaakov Sorry, but I'm pretty sure that your explanation for this *specific* case is wrong. The Wurth part you chose has a *nanocrystalline* core which has significantly different complex permeability characteristics to conventional ferrites. In particular it has a much broader frequency range, 200kHz to 200MHz according to a Wurth presentation. Unfortunately I can't find the permeability data on Wurth's site but I found a good paper at pubmed (NIH). I can't post a link here but searching for 29360754 will easily find it. Figures 3 and 7 are particulary interesting - the first showing that u'' is almost as high as u' from low frequencies unlike ferrites which have low u'' losses at low frequencies. (This might, in part, explain the higher than expected resistance at lower frequencies).

Have you tried Spanish subtitles ?

@@sambenyaakov voy a ver si existe

Thanks