The Microchip Technology Inc. 25AA256/25LC256 (25XX256*) are 256 Kbit Serial Electrically Erasable PROMs. The memory is accessed via a simple Serial Peripheral Interface (SPI) compatible serial bus. The bus signals required are a clock input (SCK) plus separate data in (SI) and data out (SO) lines. Access to the device is controlled through a Chip Select (CS) input. Communication to the device can be paused via the hold pin (HOLD). While the device is paused, transitions on its inputs will be ignored, with the exception of Chip Select, allowing the host to service higher priority interrupts. The 25XX256 is available in standard packages including 8-lead PDIP and SOIC, and advanced packaging including 8-lead DFN and 8-lead TSSOP

Parameter Name	Value
Density	256 Kbit (x8)
Op. Volt Range (V)	2.5 to 5.5
Max. Clock Freq.	10 MHz
Page Size (bytes)	64
Write Protect	Quarter, Half, Whole Array
Temp Range (°C)	-40°C to +150°C
Endurance	1,000,000

  25AA256/25LC256 Device Data Sheet