More info required: What is precision of the DAC, in bits (8 - 18) or volts (1mV - 0.5V); How fast do you need to check on your voltage from input?
1) Which method do you recommend for my application? R/2R Ladder or the one using the op amp?
2) Can the ADC output an DC voltage (0 to 5V) ?
3) Am I using the PWM output pin to achieve the process of DAC?
2) Can the ADC output an DC voltage (0 to 5V) ?No the ADC outputs nothing it is an input.