pic microcontroller discussion list wrote:

>
> For the third time: I just want VERY LOW noise,

And as quoted by Olin:
>> Alessandro Queri wrote:
>>> I want no noise in the _50Khz_+_ band, (+!).
>>

That's his point. You said you wanted no noise. And
he told you that this was impossible.

Anyway, now that you want "very low noise" you need
to specify that. For your application, what is very
low noise? Notice that I'm asking the same question
that Olin asked. Why do you think that is?

Now, on to actually being somewhat helpful:

If you only have 5V available, you need a switching
regulator or some sort. So you generate a higher
voltage than you need, and clean up the noise with
linear regulators.

Will the linears be clean enough for you? No one
knows unless we know how much noise you can
tolerate. If the linears aren't enough, then you
can add additional filtering and resort to
RF beads to kill more of the switching noise.

Phil Eisermann
Electronics Engineer
The Ridge Tool Company
(440)329-4680

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