I'd like to build a bench power supply for prototyping and development work. Most of the benchtop power supply designs I have seen are based around a transformer, rectifier and linear regulator (eg 7805/LM317).
However, I like the idea of keeping it efficient, so am interested in building something switchmode instead.
My work is mainly microcontroller-based, but I mess around with audio stuff from time-to-time too. I'm thinking that a 3-rail design (±15V to 0V adjustable, +5V, up to 1A) would cover most things.
Would the increased ripple voltage of a switchmode power supply make it unsuitable for general-purpose use?
Or, given that I'll be relying on this power supply for a lot of future work, should I stick with the simplicity of a linear regulator design?
Best Answer
If your output voltages are fixed you should be able to design it with linear regulators with a minimum of voltage drop over the regulators. And 1A is not the end of the world.
A switcher would be more appropriate if you have a variable output voltage. A linear regulator which can supply 30V @ 5A, but which is set to 1V out it will have to dissipate 150W.
An SMPS is dimensioned for a certain input voltage, output voltage and current. If you would vary the output voltage its efficiency will be lower. You won't get the 90% figure manufacturers boast about over you full range, maybe more like 75 to 80%.
edit
If you want the +/-15V adjustable I'd go for the SMPS, for the dissipation reason I mentioned. You can attack the ripple with a pi-filter. A high frequency switcher (like 1.5MHz) will allow for a smaller coil.