DS1249W

19-5633; Rev 11/10 www.maxim-ic.com FEATURES  10 years minimum data retention in the absence of external power  Data is automatically protected during power loss  Unlimited write cycles  Low-power CMOS operation  Read and write access times of 100ns  Lithium energy source is electrically disconnected to retain freshness until power is applied for the first time  Optional industrial (IND) temperature range of -40°C to +85°C  JEDEC standard 32-pin DIP package DS1249W 3.3V 2048kb Nonvolatile SRAM PIN ASSIGNMENT NC A16 A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 32 VCC 31 A15 30 A17 29 WE 28 A13 27 A8 26 A9 25 A11 24 OE 23 A10 22 CE 21 DQ7 20 DQ6 19 DQ5 18 DQ4 17 DQ3 32-Pin Encapsulated Package 740mil Extended PIN DESCRIPTION A0–A17 - Address Inputs DQ0–DQ7 - Data In/Data Out CE - Chip Enable WE - Write Enable OE - Output Enable VCC GND - Power (+3.3V) - Ground NC - No Connect DESCRIPTION The DS1249W 2048kb nonvolatile (NV) SRAMs are 2,097,152-bit, fully static, NV SRAMs organized as 262,144 words by 8 bits. Each NV SRAM has a self-contained lithium energy source and control circuitry that 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. There is no limit on the number of write cycles that can be executed, and no additional support circuitry i...