The DS1258W 3.3V 128k x 16 Nonvolatile SRAM is a 2,097,152-bit, fully static, nonvolatile SRAM, organized as 131,072 words by 16 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry, which constantly monitors VCC for an out-of-tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent data corruption. DIP-package DS1258W devices can be used in place of solutions which build nonvolatile 128k x 16 memory by utilizing a variety of discrete components. There is no limit on the number of write cycles that can be executed and no additional support circuitry is required for microprocessor interfacing. * 10-Year Minimum Data Retention in the Absence of External Power * Data is Automatically Protected During a Power Loss * Separate Upper Byte and Lower Byte Chip Select Inputs * Unlimited Write Cycles * Low-Power CMOS * Read and Write Access Times as Fast as 100ns * Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time * Optional Industrial Temperature Range of -40°C to +85°C, Designated IND