From: invalid@invalid.invalid   
      
   On Sat, 10 Sep 2016 12:19:34 -0700, Big Bad Bob wrote:   
      
      
   >   
   > you know, 'correct way' is rather arrogant.  the CORRECT way [in my   
   > view] is the method that uses the FEWEST components, is easiest and   
   > cheapest to build, and has the highest amount of flexibility.  That   
   > would exclude using up one of the PWM outputs to generate a reference   
   > voltage, when they're already being used for "other things"...   
      
      
   OOH! :)   
   Surely, when you want a high accuracy power supply the correct way is to   
   produce one, even if that means using a cheap pwm output? ;)   
      
   You could probably use a switcher as a tracking pre-reg to feed an   
   analogue voltage regulator, the pre-reg keeping the analogue reg input   
   about 10V higher than it's output. Then regulate the analogue reg from a   
   pwm-produced ref supply. That would, of course, make your voltage   
   adjustable in 1023 steps, but the low frequency stability would be   
   better. The main problem that I can see is HF noise from the switcher   
   getting through the analogue reg, but you'd have had that anyway. Some   
   careful layout and an LC filter between the stages might work.   
      
   PWM isn't ideal anyway, but in this case it would be worth a try. Good D-   
   A conversion above 10-bit is expensive and probably wouldn't be justified.   
      
   Sorry I didn't reply earlier, I've been away from home for a few days.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)