Timeline for Why are common mode chokes with 90 ohm @ 100 MHz recommended for USB 2.0 Hi-Speed data lines?
Current License: CC BY-SA 4.0
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Mar 30, 2021 at 14:01 | comment | added | CatastrophicFailure | 1. Yes, agree. 2. This is something I experienced differently. I’ve seen many commercial designs incorporating such devices. Also, manufacturers have quite a remarkable lineup on CM chokes and TVS diodes for USB application which must be profitable somehow (my opinion) 3. This is weird but you’re right. They specify the COMMON-MODE impedance to 90 ohms instead of the DIFFERENTIAL-MODE impedance to be 90 ohms. WHY? 4. Seems right but bigger chokes again have also much lower differential impedance than 90 ohms which is worse again. Would imply there is no way to build reasonable devices | |
Mar 30, 2021 at 2:39 | history | edited | Ale..chenski | CC BY-SA 4.0 |
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Mar 30, 2021 at 2:35 | comment | added | Ale..chenski | See also murata.com/~/media/webrenewal/products/emiconfun/mail/2011/09/… for many variants of CMCs and their differential impedance characteristics | |
Mar 30, 2021 at 2:25 | history | answered | Ale..chenski | CC BY-SA 4.0 |