High-Speed 256 Kbit SPI F-RAM for Industrial Applications with Wide Operating Range The FM25W256-GTR is a 256-Kbit (32K × 8) serial ferroelectric RAM (F-RAM) with a high-speed SPI interface, offering nonvolatile storage, 100 trillion read/write cycle endurance, and 151-year data retention at 65°C. It operates from 2.7 V to 5.5 V across –40°C to +85°C, supports up to 20 MHz SPI clock, and features NoDelay™ writes for instant data storage.