[sdiy] as3340 PW/tuning issue

ColinMuirDorward colindorward at gmail.com
Wed Dec 18 20:44:39 CET 2019

Thanks Jay and Dave.
I found some muffs threads. In one of them, alfa (presumably alfa rpar
spokesperson) chimed in to say that the issue would be corrected in future
Dave, you added a -5v regulator, is that to power the 3340, or as a
reference voltage somewhere, or both? I know the datasheet suggests
powering from -5v to reduce self heating, but did not mention effect on pwm.

On Wed, Dec 18, 2019 at 4:58 PM Jay Schwichtenberg <jschwich53 at comcast.net>

> Colin,
> There has been a lot of talk and info on this in Muff Wigglers. Go there
> and do a search.
> Seems that the different (manufactures) 3340s behave differently and from
> what I've seen the AS3340 is the worst. There are things that can be done
> to minimize the problem, that's been documented on Muff's.
> Jay S.
> On 12/18/2019 10:31 AM, ColinMuirDorward wrote:
> Hi folks,
> Was there ever a conclusive investigation of the PW/pitch interaction on
> the as3340 chip? What I mean is that when you adjust the pw, you get some
> detuning as well.
> I've never been sure if this was a bug in my circuit or the chip itself.
> Also not sure if the other 3340 versions exhibit the same behavior. I asked
> someone to test on their ms101 if that issue was evident, and they said "no
> detune".
> I know that I'm not the only one experiencing this since alfa rpar sells a
> module "for circuits where requirements on influence of PWM signal on
> frequency are strict <http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php> "
> Any thoughts welcome.
> Cheers,
> Colin
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