Magnetic field immunity of Spin-Transfer-Torque MRAM
SPINTEC contributed to an application note just published in IEEE Electrons Devices Magazine (September 2024 issue) which discusses the working principle of spin-transfer torque magnetoresistive random access memory (STT-MRAM) and the impact that magnetic fields can have on STT-MRAM operation. Sources of magnetic field and typical magnitudes of magnetic fields are given. This application note is also available in open access on arXiv: https://arxiv.org/abs/2409.05584
Based on the magnitude of commonly encountered external magnetic fields, it is shown in this note that magnetic immunity of STT-MRAM is sufficient for most uses once the chip is mounted on a printed circuit board (PCB) or inserted in its working environment. This statement is supported by the experience acquired during 60 years of use of magnetic hard disk drives (HDD) including 20 years of HDD with readers comprising magnetic tunnel junctions, 20+ years of use of magnetic field sensors as position encoders in automotive industry and 15+ years of use of MRAM. Mainly during chip handling does caution need to be exercised to avoid exposing the chip to excessively high magnetic fields. In current products, STT-MRAM chips can operate without error in fields up to a few tens of mT to one hundred mT depending on MRAM target application (10 mT corresponding to 100 gauss in centimeter-gauss-seconds, or CGS units). The magnetic environment can be easily checked by using a Hall probe setup. In addition, in very special cases where the risk of exposure to very high magnetic field exists, solutions can be used such as chip magnetic shielding and guarding, by design, a distance to avoid any close presence of permanent magnets.?
Conseils utiles
320 US Patents, IEEE Fellow, Designed and developed GMR heads -Patents and publications available on Google Scholar and Semantic Scholar
4 周Great comments!!!! Thanks to all!!!
320 US Patents, IEEE Fellow, Designed and developed GMR heads -Patents and publications available on Google Scholar and Semantic Scholar
4 周Thanks to all for.!!!!!!
Managing Director at MemXcell
4 周Interesting article and conclusion on automotive use-cases - I made a similar analysis a few years ago (available at memXcell.com) which include also the wireless charging use-case. To expand MRAM use in automotive and consumer applications, we first need an agreed standard procedure for determining the magnetic immunity of a given memory. NVM vendors/foundries should include this as part of the reliability qualification in addition to endurance, retention and disturbs. Today the SoC designers are left with too many questions when considering MRAM, which can only be addressed if they have extensive NVM experience in-house. A Magnetic Immunity extension to JEDEC or AES Q100 would be ideal.