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PWM to Analog DC Voltage Converter Chip for Arduino

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Hello all!  I am working on a project that uses serial commands to control a voltage controlled gain op-amp.  I am using the Arduino to receive and process the serial commands and slowly working through the needed programming.  On the output side of the Arduino I need to find a way to convert the 5V PWM outputs into a clean 0-4v DC signal, what the VCA op-amp needs.  I have seen various designs on the web using a RC network to accomplish this, but I have to believe that there is a chip out there that would do it more precise and all in one nice package.  Anyone know what I should be looking for or some specific recommendations?  Thanks!

why do you need a chip if a simple RC network (fancy name for two basic parts) will do the job ?

Well you can buy a nice 5th order filter chip, or just buy a DAC chip which will give you an output that won't need filtering in roughly the same space-but as Simon says, why use that instead of an RC filter?

It honestly comes from to my lack of knowledge of caps and RC circuits in general.  Usually an IC datasheet gives me enough information that I can figure out how to interface the chip into a workable circuit.  If it's not something that exists on a chip, I can certainly play around with some caps and RC circuits and eventually find a workable solution.  Just trying to find an easier way to get to a solution.

I agree an RC is ideal.

What's the PWM frequency and signal being modulated?

If you use a single RC filter with a cut-off of 1/100 of the PWM frequency you'll have virtually no ripple or you could use two RC filters one after the other with the cut-off at 1/10 of the PWM frequency for similar performance.

An op-amp configured as a non inverting amplifier could be used to reduce the output impedance of the circuit.


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