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PWM to Analog DC Voltage Converter Chip for Arduino

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beaker353:
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!

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

DaveW:
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?

beaker353:
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.

Zero999:
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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