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<div dir="auto">Yeah an rc low pass filter is the way to go. I've done it that way many times. The unity gain op amp could give you a buffer on the filter output, but I think ADCs are usually high impedance inputs. Depending on how fast you need the signal to change could impact what op amp you would need to use. You could play around in LT spice with different frequencies and component values to find something that works. Pete would know better than me, but I think the downside to higher frequency might be higher power draw, since more of the signal is going through the cap in the filter.</div><div dir='auto'><br></div>
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<p style="color: black; font-size: 10pt; font-family: sans-serif; margin: 8pt 0;">On June 29, 2020 10:32:55 PM Pete Soper via TriEmbed <triembed@triembed.org> wrote:</p>
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The classic way to do this is with a low pass filter. If you google "PWM DAC" you'll find what you need. But the performance is going to be a function of the PWM frequency and how precisely you can change the duty cycle.<div dir="auto">Pete</div><div><br></div><div style="font-size:100%;color:#000000" dir="auto"><div>-------- Original message --------</div><div>From: Charles A via TriEmbed <triembed@triembed.org> </div><div>Date: 6/29/20 10:23 PM (GMT-05:00) </div><div>To: triembed@triembed.org </div><div>Subject: [TriEmbed] PWM to Analog 0 to 5 VDC? </div><div><br></div></div><div dir="ltr">Anyone have a favorite circuit or chip to convert a PWM signal to a 0 to 5 VDC signal? The resulting voltage needs to be very stable. It feeds an ADC input. I've looked at an RL circuit into an OpAmp that also has a cap to ground at the OpAmp input. The DVM says it's stable but the ADC reading the voltage says it's not. I'm measuring 100 mV deviations. Would like to get to a 10 mV deviation. I've tried changing cap values on the input as well as adding caps on the output side of the OpAmp. Made improvements but still not good enough. So looking for suggestions please.<div><br></div><div>Thanks,</div><div>Chuck</div></div>
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