The concept of using a PWM into an integrator (i.e. low pass filter) is old tried and true method. Really nothing magic here. You have to watch out for several factors...

- Range of signal voltage is limited to the high and low drive levels of the digital PWM signal. These can vary with loading on the signal and the drive levels may be sensitive to temperature.

- Analog bandwidth of the signal is quite a bit lower than you can achieve with a parallel D/A circuit due primarily to the PWM signal frequency and the time constant of the filter required to achieve the acceptable amount of ripple on the output signal.

- PWM signals generally share the digital GND of the MCU and so may have more noise than an implementation with an MCU with a regular D/A supported by separate analogue VDD and GND pins.

Michael Karas