256 Mbit SPI NOR flash in an 8-WSON exposed-pad package
The S25FS256SAGNFI000 is a 256 Mbit SPI NOR flash from Infineon's FS-S series, organised as 32M x 8 bits and accessed through a Quad I/O SPI interface that also supports QPI mode for reduced command overhead on random reads. Clock frequency is rated at 133 MHz — in Quad I/O mode this gives a sustained read throughput that supports execute-in-place (XIP) for Cortex-M class microcontrollers without a separate DRAM buffer. The supply voltage window is 1.7 V to 2 V, which means the board's 1.8 V rail must hold regulation within ±200 mV across load transients; a 1.8 V ±10 % regulator that dips to 1.62 V on a current step will drop the part out of spec.
Mounting is surface-mount per the standard WSON footprint; the exposed pad is electrically connected to the die substrate and should be tied to ground or left floating per the datasheet recommendation. The tray packaging is suitable for volume pick-and-place, though the part is also available in tape-and-reel through alternate order codes in the FS-S family.
The -40°C cold-start guarantee means the flash reliably initialises after a freeze-thaw cycle — important for outdoor gateways and unheated cabinets in northern climates.