Here is a circuit that allegedly converts PWM into a precision voltage reference:
I am thinking about feeding that reference into the reference line on this MCP4921 DAC. My goal is to generate waveforms that use the entire range I need (0-2v) and be able to digitally adjust the volume or max output level without losing the 12-bit precision. An option I hope to avoid is using 1 or 2 digipots on the output. For example, I could generate a 1v sinewave (instead of the maximum 2v), but the wave would not have as high a resolution as if I generated a full sine wave, but with respect to a 1v reference instead of 2.
I'm also hoping this circuit will help me avoid using 1 DAC as the reference to a 2nd DAC.
Is it even acceptable to vary the reference on the DAC, or is it meant to be constant? From what I can see, it seems doable.
Am I totally off track? Is there a better way to solve this problem?
Assuming that this is a possible solution and I'm not totally off track, how would you go about converting the +-2495mV range to a 0-2495mV single supply range? I'd like to be able to adjust this reference as high-res as possible within that range using the PWM from the uC.