Using PWM Output as a Digital-to-Analog Converter

http://www.ti.com/lit/an/spraa88a/spraa88a.pdf

http://www.ti.com/litv/zip/spraa88a

The high-resolution PWM on the TMS320F280x DSP family has been used to implement a digital-to-analog converter
with the addition of an external analog low-pass filter.

Such an approach can offer a lower-cost alternative to a dedicated DAC chip. Using a 2nd order passive RLC filter,
greater than 9 bits DAC resolution is achievable while still maintaining 100 kHz bandwidth.

Alternately, greater than 10 bits of DAC resolution is achievable with 50 kHz bandwidth by modifying the filter component values.

This is sufficient resolution and bandwidth for adoption in a wide variety of applications.