The Cypress FM25H20-G is a 2 Mbit ferroelectric RAM (FRAM) in an 8-pin SOIC package, organised as 256 K × 8 bits and accessed over a 40 MHz SPI bus. FRAM is non-volatile and writes complete in a single bus cycle with no erase-before-write delay.
40 MHz SPI — bus timing and throughput
The 40 MHz SPI clock supports sequential reads and writes at up to 40 Mbps. Unlike serial Flash, there is no page buffer or sector-erase latency — every byte write completes in the same bus cycle as a read. For a design that logs sensor data or stores configuration parameters in a tight loop, this eliminates the write-time jitter that Flash introduces.