8 Replies Latest reply on Aug 14, 2012 6:26 AM by user_14586677

    How to blow a hole in a PSoC 5


      I designed a board for a client of mine, and the board uses a PSoC 5 chip.


      I got a whole load of boards made at a contract manufacturer and the client began testing them.


      They all worked really well, except one small issue with one board, which I thought would be something simple.


      The issue with the one board was that it could only be programmed with the 5-Pin header. When hooked up via USB windows did not detect the device at all, so it could not be programmed with BootloaderHost - and the customer needs to be able to flash via USB.


      I got the board sent up to me for further investigation.


      The board powered up OK, and ran though all the self tests perfectly, with the one exception that it did not appear as a USB device during boot. I thought it'd just be a connector or soldering issue.


      When I looked a bit closer at the board I discovered that 7 capacitors were missing around the PSoC - in fact, all the 100nF caps were missing on the power rails going to the PSoC. For some reason yet to be determined, the manufacturer had missed off the decoupling caps at the PSOC.


      Then I noticed somethint else, something far more interesting - there is a small, but deep hole in the top of the PSoC. Yip a small hole in the chip! It has a bit of charing around it. I assume something has gone POP inside the chip. It is strange that the only function not working is USB! I have attached a photo and you can just about make out the hole in the PSoC chip - and this board still works - all apart frm the USB functions!


      This device only connects to GND, D+ and D- of the USB connector. The +V pin on the USB Type B connector is not used since we do not source any power from the USB host.