256 Kbit SPI EEPROM — what the 20 MHz clock buys the bus
The Microchip AT25256B-MAHL-E is a 256 Kbit serial EEPROM with an SPI interface clocked at 20 MHz. Organized as 32K x 8, it stores non-volatile configuration, calibration, or firmware parameters that need field updates. The 20 MHz SPI rate means a full 32 KB read completes in about 13 ms — fast enough for boot-time parameter fetch or OTA staging without stalling the host MCU.
Supply range and temperature — which designs it fits
The supply range spans 1.8V to 5.5V, so this part works on 3.3V and 5V logic rails equally, and the 1.8V floor lets it run from a single Li-ion cell or a 1.8V core supply in low-power designs.
Package and footprint — 8-UDFN with exposed pad
The tape-and-reel and cut-tape options cover both prototype and production volumes.
Write cycle time and memory interface
The SPI interface supports the standard opcodes (WREN, WRITE, READ, RDSR, WRSR) and a byte-write or page-write mode. For firmware updates that write several hundred bytes, page writes cut the total programming time versus byte-by-byte writes.
For dual-sourcing or a pin-compatible alternate, the AT25256B-SSHL-T uses the same die in an SOIC-8 package — the SPI interface, 20 MHz clock, and 256 Kbit density are identical, only the footprint changes.