3 Replies Latest reply on May 4, 2017 9:39 AM by JoMe_264151

    ADC delsig functioning



      I am trying to use to the ADC Delsig component in PSoC 5. Vdda on the board is 3.3V. With the ADC Delsig I want to read voltage value in the range 0 - 3.3V. Delsig is configured to work 'single ended'.


      Delsig  settings:


      Conversion mode: multi sample (I have more than one voltage value to read)


      Resolution (bits) : 17


      Input range : 'Vssa to Vdda'


      Reference (Vref) :'Internal Vdda / 3 (1.1V)' (only option available not considering the external bypass capacitor)


      Gain : 1


      Buffer mode : Rail to rail


      I am testing the circuit imposing voltage value to the ADC (from 0 to 3.3 in steps of 0.1V). I can not see any variation in the ADC delsig output when input voltage value exceed about 2.1V. In addition I can not understand how to calculate LSB amplitude (V) in order to convert the delsig output  (digits) to V.


      Actually I am using this formula :


      LSB= (Vdda-Vssa)/2^resolution 


      output_v = output_digit * LSB


      There is something wrong because using this formula input step of 0.1 V results on an output step of about 0.15V.


      Thank you.