X25401

APPLICATION NOTE A V A I L A B L E X25401 256 Bit AN56 X25401 SPI Serial AUTOSTORE™ NOVRAM 16 x 16 Bit FEATURES DESCRIPTION The Xicor X25401 is a serial 256 bit NOVRAM featuring a static RAM configured 16 x 16, overlaid bit-by-bit with a nonvolatile E2PROM array. The X25401 features a Serial Peripheral Interface (SPI) and software protocol allowing operation on a simple three-wire bus. The bus signals 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, allowing any number of devices to share the same bus. The Xicor NOVRAM design allows data to be transferred between the two memory arrays by means of software commands or external hardware inputs. A store operation (RAM data to E2PROM) is completed in 5ms or less and a recall operation (E2PROM data to RAM) is completed in 2µs or less. The X25401 also includes the AUTOSTORE feature, a user selectable feature that automatically performs a store operation when VCC falls below a preset threshold. Xicor NOVRAMs are designed for unlimited write operations to RAM, either from the host or recalls from E2PROM and a minimum 1,000,000 store operations. Inherent data retention is specified to be greater than 100 years. 1MHz Clock Rate AUTOSTORE™ NOVRAM —Automatically Performs a Store Operation Upon Loss of VCC Single 5 Volt Supply Ideal for use with Single Chip Microcomputers —Minimum I/O Interface —SPI Mode (0,0 & 1,1)...