1. The Embedded Compression Dump OCI Investigations

2. OCI Investigation -Slide 2 OCI – Aug 2007Crouch Requirement-Definition What is Compression Dump? During a diagnostic mode – the storage of bypass patterns for use at some later time is not palatable for many customers The reliance on a vendors particular solution is not palatable The use of simulation in a Fab or FA environment to determine the logic related to a reported fail is not always possible There are many tools/vendor-solutions available if the Patter/Chain/Bit of scan chains is available

3. OCI Investigation -Slide 3 OCI – Aug 2007Crouch The JTAG Shadow Architecture SDO[0:n] TDO SDO[0:n] DeCompressorDeCompressor CompactorCompactor TDI Expect In Diagnostic mode, when a Fail occurs the JTAG Shadow Register Captures the State of the last set of flops that feed the Compactor – this allows Pattern/Chain/Bit to be rebuilt since Pattern & Bit are known; if the compactor has pipelining then the pattern must be re-applied and captured at the cycle when the fail enters the compactor

4. OCI Investigation -Slide 4 OCI – Aug 2007Crouch IJTAG Capture Cell Logic SDI from prev Scan Cell Scan Clk Last Scan Flop that feeds Compactor To Compactor JTAG TCK or Scan Clk Fail_Enable Capture-DR Shift-DR TDI from prev JTAG Cell TDO to next JTAG Cell

5. OCI Investigation -Slide 5 OCI – Aug 2007Crouch The Real-Time Bypass Architecture In Diagnostic mode, when a Fail occurs the Compression Architecture converts to the bypass architecture – the ATE must go into data capture mode. To allow full-data collection, it is best to run the architecture up to before the Sample and to dump the apply vector; then run it again and dump the response vector; the golden state is from dumping a good/golden part SDO[0:n] DeCompressorDeCompressor CompactorCompactor Expect