<div dir="ltr"><div>OK I found the answer to this in the TH vco maximus thread at muffs.</div><div>User chrissugar reports " So as a conclusion the goal is to have on pin3 as close as possible to -5V and the PWM to tune error will not manifest itself."</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Dec 18, 2019 at 2:44 PM ColinMuirDorward <<a href="mailto:colindorward@gmail.com">colindorward@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div>Thanks Jay and Dave.</div><div>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 versions.</div><div>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.</div><div>Colin<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Dec 18, 2019 at 4:58 PM Jay Schwichtenberg <<a href="mailto:jschwich53@comcast.net" target="_blank">jschwich53@comcast.net</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Colin,</p>
<p>There has been a lot of talk and info on this in Muff Wigglers.
Go there and do a search.</p>
<p>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.</p>
<p>Jay S.<br>
</p>
<div>On 12/18/2019 10:31 AM,
ColinMuirDorward wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Hi folks,</div>
<div><br>
</div>
<div>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. <br>
</div>
<div><br>
</div>
<div>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".</div>
<div><br>
</div>
<div>I know that I'm not the only one experiencing this since
alfa rpar sells a module "<a href="http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php" target="_blank">for circuits where requirements on
influence of PWM signal on frequency are strict</a>
"</div>
<div><br>
</div>
<div>Any thoughts welcome.</div>
<div><br>
</div>
<div>Cheers,</div>
<div>Colin<br>
</div>
<div><br>
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