3 Replies Latest reply on Aug 20, 2013 12:31 AM by ki.leung

    PC (Program Counter) corruption after power off

              After 2 weeks of work the chip suddenly failed after power off. PC jumps to strangle locations. The whole flash is write protected. The only thing I occasionally write is EEPROM.   
        • 1. Re: PC (Program Counter) corruption after power off

          As far as I know, most devices fail when they are switched On!


          I would suggest to read-out the flash and compare it with the desired hex. When you have debugging capabilities integrated to your board you even may inspect the memory contents.





          • 2. Re: PC (Program Counter) corruption after power off

            Suspect as always is tranients on I/O pins that inject charge into the


            substrate, and potentially corrupt FLASH cells. Or transients on Vdd


            that exceed gate ox breakdown. Best way of detecting a condition like


            this is a DSO set to trigger on something like this -




            Vss - .7V >  Vtrig > Vdd + .7V




            and look at key interface pins talking to loads than can generate


            transients, like a relay, a MOSFET driving a relay (transient feedback


            thru Cgd). Set up jig to cycle power, and enable DSO on signal that


            triggers power up and down.




            This is vary tedious to find, patience is a virtue.




            Also in general power supply sequencing, make sure PSOC comes up


            before any I/O loads do. If you cannot guarentee that make sure all pins


            clamped by zener arrays, avaialable from On Semi, Vishay, Fairchild to


            name a few.




            Regards, Dana.

            • 3. Re: PC (Program Counter) corruption after power off

              How do you find the PC corrupted?


              Would there be some cases where your EEPROM value is out of your expected range and your program perform not as you expected?