[time-nuts] Switching regulator replacement for 7805

Scott Stobbe scott.j.stobbe at gmail.com
Sun Dec 4 16:22:02 EST 2016

If you wanted to be nutty you wouldn't go PWM at all, just like
fractional-N sythns don't just mash 2 divider values. You would sigma-delta
modulate your power stage. I don't know if you can buy one COTS, but there
are plenty of papers on rolling your own.

On Sun, Dec 4, 2016 at 4:09 PM, Attila Kinali <attila at kinali.ch> 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
> in the QFN packages, as those have shorter leads and a large ground pad
> to keep EMI down. But soldering an 0.5mm QFN by hand is impossible
> (believe me, I tried) and not everyone has an oven. Also a lot of the
> EMI performance depend on what output current you expect. Using a 1A
> design for 10mA is a good way to get poor EMI performance as the
> chip will go from PWM (aka fixed frequency) to PFM (aka fixed on time)
> mode under low load to increase efficiency. The same goes for input
> voltage. So we would need to do multiple designs for different
> output current and input voltage ranges... which kind of defeats
> the purpose of "a small board that drops into....".
> What could be done, though, is a small board with all components,
> but the inductor on it. So then one could select the right inductor
> for the application and solder it on. Using an inductor that is easy
> to solder (like e.g. WE-PD3) with a wide selection of values should
> do the trick.
>                         Attila Kinali
> --
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>                  -- Miss Matheson, The Diamond Age, Neil Stephenson
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.

More information about the time-nuts mailing list