[sdiy] switched mode PSU design

[Mark Smith]

>Old-fashion pi filters (C-L-C) can do miracles... don't know why they
>aren't used anymore. (cost? space?..) 


...thats all we use in my day job, good old fashioned pi filters and maybe a low dropout linear reg where absolutely necessary (usually a high speed PLL/vco cct).

Our designs are all switcher based and we always achieve better than 90dB snr for audio and over 70dB on video. The digital frontends are way more susceptable to noise, and very rarely does the power supply ever cause any trouble. In fact I can't ever recall ever hearing any 100KHz switching artifacts on audio - I can see them on video if theres a problem though.
Most power supply problems I have on audio are hum or other circuits influencing the low end frequencies, but never the power supply.

switchers rules !

(ducks and runs)

mark