512Kbit FRAM — SPI at 40 MHz
The FM25V05-GTR is a 512Kbit ferroelectric RAM (FRAM) from the F-RAM series, organized as 64K x 8 bits and accessed via an SPI interface running at up to 40 MHz. FRAM combines non-volatile data retention with write speeds and endurance that outpace EEPROM or flash — no page buffers, no write-cycle delays, and 10^14 read/write cycles typical.
The SPI bus uses four signals (SCK, MOSI, MISO, /CS) plus supply and ground; the 40 MHz clock rate keeps the bus timing within reach of most MCU SPI peripherals without external level shifters at 3.3 V.