View ds1230ab datasheet:

DS1230Y/AB 256k Nonvolatile SRAM www.maxim-ic.com FEATURES PIN ASSIGNMENT 10 years minimum data retention in the A14 1 28 V CC absence of external power A12 27 WE 2 A7 3 26 A13 Data is automatically protected during power A6 4 25 A8 loss A5 5 24 A9 Replaces 32k x 8 volatile static RAM, A4 6 23 A11 A3 7 22 OE EEPROM or Flash memory A2 8 21 A10 Unlimited write cycles A1 CE 9 20 Low-power CMOS 10 19 A0 DQ7 Read and write access times as fast as 70 ns 11 18 DQ0 DQ6 12 17 Lithium energy source is electrically DQ1 DQ5 13 16 DQ2 disconnected to retain freshness until power is DQ4 14 15 GND DQ3 applied for the first time Full ±10% VCC operating range (DS1230Y) 28-Pin ENCAPSULATED PACKAGE Optional ±5% VCC operating range 740-mil EXTENDED (