3 Replies Latest reply on May 4, 2017 9:39 AM by user_1377889

    ADC delsig functioning

    alessandra.leonardi

      Hello,

         

      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.