A practical 256K GMR NV memory for high shock applications

Nonvolatile memory components used in shock recorders have unique requirements compared to other applications. These include fast write speeds, unlimited operation without wear-out, no data loss with high shock and power loss, and small chip size. A nonvolatile memory component that has the characteristics needed for high shock recorders and other microcontroller applications can be constructed in a cost effective and shock resistant die which is 0.25" on a side using standard CMOS processing. The 256K component described here uses giant magnetoresistive material (GMR), which provides a larger signal than anisotropic magnetoresistive material (AMR) based devices and can be used in bits scaled to sub-μm sizes. Small conventional mode bits can be used effectively in intermediate size magnetoresistive RAM (MRAM) components that fit a large microcontroller application market. Built-in dual redundant bits and spare sense lines allow a high product yield, thus providing additional potential production cost reductions. Future size reductions will occur when the pseudo spin valve bit has been sufficiently developed to be dropped into this design