5 Replies Latest reply on Nov 24, 2020 12:07 AM by AikoO_51

    About the Cp range supported by CapSense component Ver7

    NaMo_1534561

      Hello,

       

      The new component adds a Gain IDAC parameter, which allows user to adjust the IDAC current value over a wider range. (37.5nA / bit to 4800nA / bit)

      However, in the component datasheet, the Supported Sensor Cp range remains min:5, max:45.

       

      By adjusting the Gain IDAC parameter when Auto-Calibration is enabled, I think it is possible to handle sensors with Cp exceeding 45pF by increasing the Gain. (I think that the calibration is being executed while changing the Gain with the function CapSense_CSDCalibrateWidget (uint32 widgetId, uint32 target).)

       

      Why doesn't the Cp range supported by Auto-Calibration extend?

       

      Best Regards,

      Naoaki Morimoto

        • 1. Re: About the Cp range supported by CapSense component Ver7
          AikoO_51

          Please refer to KBA229074 about IDAC current.

          According to this KBA, IDAC gain is a value for calculating IDAC current and it would be set as 2.4 µA /bit, 300 nA /bit or 37.5 nA /bit on CSD v2.

          To enable Auto-Calibration, IDAC current is calibrated by adjusted IDAC code.

          Also Cp is fixed system value.

          What document did you refer to for “37.5nA / bit to 4800nA / bit” ?

          Also could you give more details about the request on your project.

          • 2. Re: About the Cp range supported by CapSense component Ver7
            NaMo_1534561

            Hello AikoO_51-san,

             

            We can choose the Gain IDAC value from 35.7uA/bit to 4800nA/bit on the Widget Detail Tab of CapSense v7.0 component.

             

             

             

            The customer's application has a large capacitance due to the metal chassis near the sensor.

            They use Manual Tuning method because the limit that Smart Sense can tune is up  to 45pF.

            If CapSense can tune a sensor of 100pF or higher with component Ver7.0, we can introduce Smart Sense to the next model.

             

            Best Regards,

            Naoaki Morimoto

            • 3. Re: About the Cp range supported by CapSense component Ver7
              XiaoweiZ_71

              The cp range supported by CapSense sensor is not not decided by CapSense component version, it is decided by the CSD hardware architecture version. PSoC4 none-S series(PSoC4100, PSoC4200,PSOC4AM, PSoC4AL) use third-generation csd architecture; PSoC 4 S-Series, PSoC 4100S Plus, PSoC 4100PS, and PSoC 6 MCU is an improved version of the previous generation CapSense architecture - the fourth-generation CapSense architecture. The differences of these two versions ad below:

              Capture.PNG

               

              In component datasheet, the Cp range remains min:5, max:45, this data is only for SmartSense tuning mode. If you use pure manual tuning mode or ida auto-calibration tuning mode, the maximum cp can be increases to 60pF(or even more).

               

               

              • 4. Re: About the Cp range supported by CapSense component Ver7
                NaMo_1534561

                Hello XiaoweiZ_71-san,

                 

                Thank you for the explanation.

                The target IC is 4000S series.

                  CY8C4025LQI-S411

                To summarize my understanding, the 4th Gen CapSense supports a Cp range of 5pF-200pF in the manual tuning method, but SmartSense can only tune up to 45pF.

                 

                If possible, please tell me about this limit.

                Is it because SmartSense does not use the entire range of CapSense parameters (IDAC range ,Resolution, etc.)?

                 

                Best Regards,

                Naoaki Morimoto

                • 5. Re: About the Cp range supported by CapSense component Ver7
                  AikoO_51

                  Yes, your understanding is correct.

                  SmartSense is intentionally just provided a setting which is required for CapSense as minimum. (5:1 SNR)

                  If Cp can be more than 45pF, it could be greater than 5:1 SNR.

                  You need to change to manual tuning when you want to adopt for your request.