| Electronics > Beginners |
| Ferrite beads in modern surface mount products |
| (1/1) |
| Dave Turner:
Hi all gurus, With current emissivity rules and the almost universal use of surface mount componemts for modern designs; how are the issues once addressed by the addition of ferrite beads to a component's leg (amongst many other issues & solutions) dealt with on modern pcbs? In the days of point to point (and/or dead bug) construction this was 'black magic' to the majority of hobbyists (and many professionals), which generally required a 'suck it and see' approach. Interested to see any answers, Dave |
| dmills:
There are plenty of ferrite beads available as SMT packages if you really need them (Sometimes useful for IO immunity and cleaning up switchmode supply ringing). However with 4 layer boards not being the expense they once were you can usually throw a plane under your routing layer and minimise the loop area (and radiation) that way instead, modern logic being 2.5/1.8/1.5/1.2/1.0V does not hurt any either. Don't forget that to be a reasonable radiator the geometry has to be bigger then about 1/8th wave at whatever frequency matters, and SMT parts are usually rather small, this helps a lot. Regards, Dan. |
| Dave Turner:
Dan Understood - less energy - less crap - it's still black magic! Cheers Dave |
| T3sl4co1l:
It's only black magic if you can't solve polynomial roots! Tim |
| dmills:
And these days we got computers for that ;D! No magic, it is just that as the frequency rises it becomes ever more apparent that the DC rules apply at a point along the conductor, that a wire is a component too, and that you cannot ignore the parasitics. Regards, Dan. |
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