I need to convert the duty cycle 250Hz (5% to 95% ) into analog voltage from external sensor (PWM sensor with low side output). See attached circuit . I use 74HC14 logic to have duty cycle in logic supply voltage range and the 2nd order low pass filter to get analog voltage for ADC.
The issue is that step respond of this filter is 0-95% -> 65ms 0->99% 130ms. In addition I have the ripple voltage of ~50mV (~ 1% of duty cycle)
DO you have any idea how to have the faster step respond and lower ripple voltage? I would like to make it as simple as possible.
In addition, I am thinking about software filter. Do you have any examples of filter which I could use to have faster step respond and reduce ripple voltage ?
What would be the middle point between filter parameters and software filtering capability for such signal to get decent accuracy /fast respond?