A user´s approach to characterization and test of commercially available SRAMs

Summary form only given, as follows. In today´s highly competitive, cost-driven market, commercial memory manufacturers are forced to increase total bit counts and densities while reducing test times. As a result, many performance parameters are now being guaranteed by design or sample testing rather than by full functional verification of each device. This situation is complicated by the drive for lower power consumption (i.e. lower supply voltage) which compromises operating margins. In addition, the consumer electronics market´s tendency to dispose of components, rather than repair them, and shorter product life cycles have reduced the manufacturer´s feedback on failure modes in typical use. This minimized approach to performance verification poses a problem for manufacturers involved in high reliability applications, such as medical implantable, military, automotive, and aerospace, who often perform additional testing on their own. To insure high reliability memory in their implantable medical electronics, Medtronic has developed a methodology for the performance verification of commercial SRAMs which accommodates the lack of design and fabrication information typically available at the manufacturer. The following points are covered: problems of black box design verification, practical methods for performance verification, example results and production test optimization