2 Replies Latest reply on Aug 8, 2012 12:22 AM by ramnath.r.k

    PSoc3 ADC Maximum Voltage.

    salman.javaid

      I am using Single Mode ADC on PSoc3 Development kit. Now even when I select Input Range upto a maximum of 6.048 volts, I am only being able to retrieve 4.023 volts on LCD as the maximum voltage. The voltages on the lower ranges like 2.87, 3 volts are correctly identified. Any help will be deeply appreciated.

        • 1. Re: PSoc3 ADC Maximum Voltage.
          user_14586677

          This note in datasheet on input Common Mode Range -

             

           

             

          VSSA to 6 × VBG range is used for direct measurement of VDDA power supply. Actual scale is limited to VDDA.

             

           

             

          This makes sense, that input range, in a CMOS device designed for R-R performance, is limited to

             

          supply rails +, if we are lucky, a diode drop.

             

           

             

          Regards, dana.

          • 2. Re: PSoc3 ADC Maximum Voltage.
            ramnath.r.k

            I agree with Daana, the Vdda limit is around 5.3V.

               

            Hence we cannot have have inputs beyond this to  the adc.

               

            The reason why we have an option of choosing up to 6 V Range is to improve the linearity of the ADC while operating in the 0 to VDDA range. Higher the range,improved is the linearity.!