3 Replies Latest reply on Aug 12, 2013 5:12 AM by user_14586677

    Design circuit with CY8C3866AXI-040

    salim.ylmaz

      Hİ,

         

      I designed new circuit using CY8C3866AXI-040. Due to an error, when trying to install the program chip can not be found. I followed the rules of the circuit design psoc3 but chip can't be found. Then I searched for the error. I found that  VDDD voltage> VDDA voltage. I measuered VDDD voltage 0.7 V. VDDA voltage is 5.2 V. So chip can't be found. When I equal to voltages with jumpers. IC quickly is heating. I could not find the cause of warming. I attach design file. Can you look at design. When VDDD = VDDA , what is the cause of warming  of IC. Thanks.

        • 2. Re: Design circuit with CY8C3866AXI-040
          junichi.hiraoka
                  Hi yılmaz   
          I can't figured out the cause of ploblem from picture of board and schematic.   
          I guess, does some pins that has a voltage was grounded?   
          Vddd is doubtful I think.   
          • 3. Re: Design circuit with CY8C3866AXI-040
            user_14586677

            If chip is getting hot most common problem is latchup, some thoughts -

               

             

               

            1) Latchup occurs when a pin is taken outside power supply voltage, eg.

               

            Vssd,Vssa > pin or pin >  Vddd, Vdda. Then chip internally has a parasitic SCR

               

            trigger shorting Vdd to Vss, and draws a lot of current obviously.

               

             

               

            Question, chip getting hot immeadiatley, power supply showing high currents

               

            immeadiately, or after CPU well into code ? Code your processor to just start,

               

            but do nothing, sit in a loop immeadiately, right after startup. If Idd does not jump

               

            to latchup condition then power system probably OK. Then suspect processor

               

            GPIO triggering some load causing a transient on a pin outside supply rails.

               

             

               

            2) You have a relay, I cannot see drive coil on schematic, I assume Q1 is driving it

               

            and D50 is strapped across coil to suppress turnoff transients ? Check Q1 collector

               

            with scope, to see it never transients outside Vddd, Vdda or < Vssd,a. Set scope

               

            up to trigger on 5.5 initially, then - .5, to see if you ever get a transient outside power

               

            supply rails. If your scope has deep memory trigger off init of power supply and look

               

            at each pin (tedious) to see if you can qualify a trigger outside supplie rails.

               

             

               

            3) Look at ground points around board, trigger off  main ground reference , -.5, to

               

            see if you can get a trigger. This is difficult as you would need to cycle power each time

               

            you look at a new pin.

               

             

               

            Some thoughts, Dana.