View ds1345w datasheet:

DS1345W 3.3V 1024k Nonvolatile SRAM with Battery Monitor www.maxim-ic.com FEATURES PIN ASSIGNMENT 10 years minimum data retention in the absence of external power Data is automatically protected during power BW 1 34 NC A15 NC 2 33 loss A16 A14 3 32 Power supply monitor resets processor when RST 4 31 A13 VCC 5 30 A12 VCC power loss occurs and holds processor in WE 6 29 A11 OE 7 28 A10 reset during VCC ramp-up CE 8 27 A9 DQ7 Battery monitor checks remaining capacity 9 26 A8 DQ6 10 25 A7 daily DQ5 11 24 A6 DQ4 12 23 A5 Read and write access times as fast as 100 ns DQ3 13 22 A4 DQ2 A3 14 21 Unlimited write cycle endurance DQ1 A2 15 20 VBAT GND Typical standby current 50 µA DQ0 A1 16 19 GND 17 18 A0 Upgrade for 128k x 8 SRAM, EEPROM or 34-Pin Powe