[sdiy] A question about regulator noise figures

[Mike Beauchamp]

On 3/15/21 8:29 PM, Tom Wiltshire wrote:
> I still don’t understand the units though. How could I convert a flicker noise measurement like 8uV/Hz to a RMS measurement across a given bandwidth like the other data sheets offer? Is that even possible? I’m starting to suspect some manufacturers don’t *want* me to be able to compare specs with their competitors! ;)
> 
> Tom


Math isn't my strong-suit (it was in university, but my brain has now 
decided to trash bin all math knowledge to make room for song lyrics). 
So for these sorts of things my suggestion is to buy a few samples of 
all the IC's that you are considering and set them up in a real-world 
comparison. Use the filter caps you intend to use, the power you intend 
to use and the load, etc and then just see what you get.

I also have to remind myself sometimes that even the scope is a limited 
tool. So if I'm picking a regulator to minimise noise in an audio 
application, the best one is the one that sounds quietest to my ears - 
which might not always be the quietest RMS reading on the scope 
depending on the nature of the noise.

Mike