[time-nuts] Switching regulator replacement for 7805

jimlux jimlux at earthlink.net
Sun Dec 4 16:34:36 EST 2016

On 12/4/16 1:09 PM, Attila Kinali wrote:
> On Sun, 4 Dec 2016 15:45:55 -0500
> Bob Camp <kb8tq at n1k.org> wrote:
>> Given that the parts to build one are fairly easy to get and that we likely have “nutty”
>> EMI requirements. Maybe a small board that drops into a 78xx footprint is the
>> better solution.
> I don't fully agree. To go full "nutty" you would want to use the chips
> i


or buy a few of each of the commercial modules and test them.  They are 
an all-in-one solution with all the usual features about overtemp, 
overcurrent, etc.

What you'd need to do is characterize their noise properties over load 
(something not in the datasheet), and then you could design a LC filter 
to knock down the rest.  Or do the LDO regulator thing.. it's not 
entirely clear that a dc/dc followed by a suitable LDO might not come 
out ahead of a dc/dc followed by a filter.

Even for time-nuts, I suspect we're not looking to eke out the last 
percent of efficiency from 96% to 97%, or handle wildly varying loads, 
etc.  Nor are we usually looking for absolute minimum parts cost.

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