Question
Are there any options for increasing the DAC resolution to greater than
12-bits?
Answer
Yes. CN0145 for the ADuC7060 shows how a PWM output can be used as a DAC. This
circuit can also be used for the ADuCM360 as it has the same 16-bit PWM.
Another option is to enable the ADuCM360 DAC interpolation mode by setting
DACCON[3]=1. Note, when using DAC interpolation an external RC filter is
required to generate a smooth DC voltage – again CN0145 should be referred to.
Note, DAC interpolation mode for the ADuCM360 does not work with DAC NPN mode
so, an external OP-AMP is required.
http://www.analog.com/en/circuits-from-the-lab/CN0145/vc.html