7 Replies Latest reply on Nov 30, 2012 9:29 PM by kishore.kumar

    Vdda and Vddd

    srihari.s

       Is there a chance that PSoC goes dead when the capacitor connected to Vdda is greater than Vdddmean to say Vddd rises early compared to Vdda? I have a board with capacitors for Vddd and Vdda are interchanged. the board was powered and PSoC didn't work. Later the capacitors wre interchanged according to spec but even then its not working. So is that my PSoC is gone????

        • 1. Re: Vdda and Vddd
          user_14586677

          There is an encyclopeida of replies to cover this toipic.

             

           

             

          CMOS has a number of parasitic There is an encyclopedia of replies to cover this topic.

             

           

             

          CMOS has a number of parasitic devices, normally “hidden” when things are biased and
          started upin the right sequence.

             

           

             

          My recommendation is to post a tech case, hopefully which will get looked at by silicon
          designer, for an answer. Most datasheets now have specific sections of specs regarding
          power sequencing, however missing explicit descriptions  as to why, what is actually
          going on.

             

           

             

          CMOS has “well isolation”  techniques, keeping devices from interacting, but  to the best
          of my knowledge, they are all accompanied by parasitic devices that, under the right
          circumstances, rear ugly heads, like the parasitic SCR mechanism that can produce a short
          internally from Vdd to Vss and typically blows open the bond wire in Vdd or Vss to the
          lead frame. Process technology actually takes into account the SCR trigger gain, beta, to
          minimize its effects.

             

           

             

          Regards, Dana.

          • 2. Re: Vdda and Vddd
            user_14586677

            Please Cypress lord, give me an HTML editor to revise my obvious post

               

            typing errors. Like we have at www.psocdeveloper.com

               

             

               

            Regards, Dana.

            • 3. Re: Vdda and Vddd
              srihari.s

               How to pose a tech case?? I have couple of things that are to be confimed with Cypress Engineers.

                 

              I don't know whether Cypress will answer some small queries.

              • 4. Re: Vdda and Vddd
                kishore.kumar

                Go to "Contact Us" -> under "Create Service Request" click "Request technical or sales support via MyCases" for creating Tech support cases.

                • 5. Re: Vdda and Vddd
                  user_14586677

                  To file a tech case -

                     

                   

                     

                  www.cypress.com

                     

                  “Support”

                     

                  “Technical Support”

                     

                  “Create a Case”

                     

                   

                     

                  Regards, Dana.

                     

                   

                  • 6. Re: Vdda and Vddd
                    user_14586677

                    To create the request you must first establish an online account

                       

                    at www.cypress.com, you will be prompted to fiull out a simple

                       

                    profile.

                       

                     

                       

                    Regards, Dana.

                    • 7. Re: Vdda and Vddd
                      kishore.kumar

                       Have you got an answer for this?