The AT45DB641E is a 1.7V minimum， serial-interface sequential access Flash memory ideally suited for a wide variety of digital voice， image， program code， and data storage applications. The AT45DB641E also supports the RapidS serial interface for applications requiring very high speed operation. Its 69，206，016 bits of memory are organized as 32，768 pages of 256 bytes or 264 bytes each. In addition to the main memory， the AT45DB641E also contains two SRAM buffers of 256/264 bytes each. Interleaving between both buffers can dramatically increase a system‘s ability to write a continuous data stream. In addition， the SRAM buffers can be used as additional system scratch pad memory， and E2 PROM emulation （bit or byte alterability） can be easily handled with a self-contained three step read-modify-write operation. Unlike conventional Flash memories that are accessed randomly with multiple address lines and a parallel interface， the DataFlash? uses a serial interface to sequentially access its data. The simple sequential access dramatically reduces active pin count， facilitates simplified hardware layout， increases system reliability， minimizes switching noise， and reduces package size. The device is optimized for use in many commercial and industrial applications where high-density， low-pin count， low-voltage， and low-power are essential. To allow for simple in-system re-programmability， the AT45DB641E does not require high input voltages for programming. The device operates from a single 1.7V to 3.6V power supply for the erase and program and read operations. The AT45DB641E is enabled through the Chip Select pin （CS） and accessed via a 3-wire interface consisting of the Serial Input （SI）， Serial Output （SO）， and the Serial Clock （SCK）。 All programming and erase cycles are self-timed.