7 Replies Latest reply on Nov 14, 2019 5:08 AM by BragadeeshV_41

    How to disign a  proximity sensor?

    user_1398601

      I want to design a proximity sensor, An92239 page 10 shows the Gnd is outside the sensor,

      92568 shows Gnd is inside the sensor,I don't know how to layout my PCB sensor? the Gnd is inside the snesor OR outside the sensor?

        • 1. Re: How to disign a  proximity sensor?
          BragadeeshV_41

          Hi user_1398601,

           

          Put the ground loop around the proximity loop for better performance. The minimum recommended width for the ground loop is 1.5 mm, and the minimum recommended clearance between the proximity sensor and the ground loop is 1 mm.

           

          Regards,

          Bragadeesh

          • 2. Re: How to disign a  proximity sensor?
            user_1398601

            Hi,BragadeeshV_41

            I want to design a rectangle sensor,the following ,which one is better?

                                                                                              figure 1

                                                                                                figure 2

            • 3. Re: How to disign a  proximity sensor?
              BragadeeshV_41

              Please answer the following questions:

              1. What are the dimensions of the loop?

              2. What is the sensing distance expected?

              3. Device selected for the application.

               

              Regards,

              Bragadeesh

              • 4. Re: How to disign a  proximity sensor?
                user_1398601

                HI,BragadeeshV_41:

                Please answer the following questions:

                1. What are the dimensions of the loop?                       longth:45cm  width:5cm

                2. What is the sensing distance expected?                    The proximity distance as far as possible

                3. Device selected for the application.                           Anti-collision detection

                • 5. Re: How to disign a  proximity sensor?
                  BragadeeshV_41

                  Hi user_1398601,

                   

                  A proximity sensor can detect only up to a max of it's diagonal (formed with the shortest side). In your case if for a 5 cm shortest side, you should be able to detect around 7 cm without ALP filters and up to 14 cm with ALP filters. Note: ALP filter support is available only for older CapSense component. (<v2.x)

                   

                  45 cm can be too long and can cause high Cp value (> 200 pF) which may not be supported by the CapSense device.

                  Instead of 45 cm length, is it possible for you to divide that into 5 proximity loops and you will be able to achieve the same performance.

                  A single ground loop can be made around all the loops.

                   

                   

                  By device, I meant the PSoC device you are going to use for this application. From your application to support this high capacitance, you may have to use a PSoC device that has latest gen CapSense in it such as PSoC 4000S, PSoC 4100S and PSoC 4100 S Plus.

                   

                  Regards,

                  Bragadeesh

                  • 6. Re: How to disign a  proximity sensor?
                    user_1398601

                    HI,BragadeeshV_41:

                    Thanks for your quick reply.

                    1. I use a CY8CKIT-042-BLE board(cy8c4247LQI-BL483)to test proximity sensor,It can detect up to 20cm without metal object.

                    CapSense component version is 2.6.

                     

                     

                    2.

                    We have metal object and motor behind the sensor,we add shield electrode to eliminate the effect of mental objects and increase the proximity distance.Do the shield electrode need link to capsnnse:shied?

                     

                    3.the sensor lay out as follows,shield electrode on the bottom

                    • 7. Re: How to disign a  proximity sensor?
                      BragadeeshV_41

                      Hi user_1398601,

                       

                      1. Okay.

                      2. Shield in the bottom layer is the best option to prevent effect of conductive objects beneath the sensor. Yes, the shield hatch needs to be connected to CapSense : Shield pin

                      3. The configuration is fine.

                       

                      Regards,

                      Bragadeesh