I can design a switcher in 5 minutes, but it will take me (as it will most) weeks or months to get it noise and EMI free. I used to say "I know no engineer that can not design a switcher, and I know no engineer that can make one work". [/quote ]

I too had a bitter experience with switchers. We are still using linear supplies for our mixed signal controllers. Some months back we decided to switch over to switchers for prototyping and testing we asked our supplier to arrange three nos custom made SMPS as per our voltage requirements. We tested them and found not suitable for our application and went back to linear. Having said this doesnt mean switchers cant be used I want to highlight the same point Erik said dont ever try to design or buy custom made unless you have lot of time for R&D go for readymade standard type available from reputed brands. Unfortunately the standard good quality readymade ones doesnt fit in our budget.


Regards,
Prahlad Purohit