rtek1000:
As for the capacitor value, in a linear source, 1000uF is usually used for each Ampere...
Only if you're converting AC to DC, not used if you're converting DC to DC. And my rule is 2200uF/A.
The smaller bypass caps are always needed. See the regulator's datasheet for best values.
Leo..
Wawa:
my rule is 2200uF/A.
Ok, this depends on which ripple is acceptable, in the case of filtering after rectification, the high value can force the rectifiers a lot.
ReverseEMF:
Well, I guess that's what I get for relying on "intuition" rather than doing the math.
But, there is a slightly better spreading of power dissipation.
I'd hardly call half-a-watt better. Especially when it can cause the problems I outlined here:
http://forum.arduino.cc/index.php?topic=545419.msg3722828#msg3722828
KOR:
but I still feel very uncomfortable having 2 additional emi sources next to my logic electronics.
Why by worried? Logic chips output tons of EMI, they don't care about SMPSs one bit, just be
sure to thoroughly decouple logic chips. Every piece of digital electronics out there is awash with
PoL buck converters, sometimes a processor is literally surrounded by multiple buck converters
each generating a different voltage rail.
Analog circuitry is another matter, power rail noise will matter for many analog purposes, like
audio, or high precision ADCs and DACs. Here its common for all the analog rails to be generated
by linear regulators.
