AT25FF321A 32Mbit SPI Serial Flash Memory Renesas / Dialog AT25FF321A 32Mbit SPI Serial Flash Memory is developed for use in a wide variety of high-volume consumer and connected applications. The AT25FF321A serial interface Flash memory device is optimized for low-energy applications. The device operates using modem Lithium battery technology over a wide input voltage range of 1.65V to 3.6V.