It doesn't actually say you can only use the Abracom part, just that is the only one they currently know of with a polarisation dot.The issue here is that the doc "Hardware design with..." goes on at some length about the problem and basically says that there is only one part from Abracom (sp?) that you can use.
This issue is well known for those building large switchmode power supplies - a 1kW solar convertor we designed had exactly the same issue - all large inductors are gapped so flux leaks out and you need it NOT to induce currents in the feedback pin. It's just much easier to avoid a large inductor being assembled incorrectly as they often have asymmetric footprints whereas an 0806 will be placed however it came on the reel, which RPi are saying is random. This seems a little odd as all diodes always face the same way for example, but they must have had it happen.
You probably could just place the 0806 inductor a little further away and either way round would do, but with a 3MHz switch rather than the more usual 500kHz to 1.2 MHz, track length can matter.
Statistics: Posted by MikeDB — Thu Aug 15, 2024 2:30 pm