3 Replies Latest reply on Aug 12, 2013 5:12 AM by DaKn_263916

    Design circuit with CY8C3866AXI-040



      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
                  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

            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.