Reliable 64kBit SPI F-RAM with 20MHz Frequency, Industrial Qualification, and Wide Operating Temperature Range of -40°C to 85°C The FM25CL64B-G is a 64-Kbit (8K × 8) serial F-RAM memory with a high-speed SPI interface supporting up to 20 MHz operation. It delivers 100 trillion (1e14) read/write cycles and 151-year data retention at 65°C, surpassing serial flash and EEPROM in write speed and reliability.