The New Age of Digital Circuit Cards Drives the Need for Innovative Automated Test Strategies

Almost all electronic systems are made up of a combination of CCAs (circuit card assemblies). The testing of these CCAs has significant impacts on system readiness and maintainability. The migration from parallel data buses to high speed serial buses has introduced many new challenges in interfacing prime hardware with test equipment. The number of low voltage power forms required on new boards to support multiple core voltages has also added to the complexity of test. Great increases in the density of integrated circuits and packages, and the amount of circuitry installed on prime hardware circuit cards makes probing difficult and even impossible in some cases. All of these factors make traditional CCA test techniques inadequate for testing and troubleshooting. This paper discusses many of the techniques being used to address the automated test needs in this new age of digital CCA test. The focus is on digital CCAs due to the fact that CCAs previously full of analog circuitry are being replaced with more and more digital circuitry. One item at the core of the new test philosophy is the use of FPGAs (field programmable gate arrays) to drive many of the tests rather than digital 10 cards in standard test equipment. The flexibility of the FPGA in communicating with numerous interfaces as well as its ability to be reprogrammed quickly makes it a key player in digital test. Also, opportunities increase greatly for BIT (built in test) and software/firmware reuse between prime hardware and test equipment. It is essential that each of the engineers and managers involved in testing systems containing circuit cards understand the impacts of the current and upcoming technology on automated test and the strategy necessary to be successful.