View ds1345ab datasheet:

DS1345Y/AB 1024k Nonvolatile SRAM with Battery Monitor www.maxim-ic.com FEATURES PIN ASSIGNMENT 10 years minimum data retention in the absence of external power 34 NC 1 BW 33 NC 2 Data is automatically protected during power A15 3 32 A14 A16 31 A13 loss 4 RST 30 VCC 5 A12 A11 Power supply monitor resets processor when 6 29 WE 7 28 A10 OE VCC power loss occurs and holds processor in 27 A9 8 CE 26 A8 9 DQ7 reset during VCC ramp-up 25 10 A7 DQ6 24 11 A6 DQ5 Battery monitor checks remaining capacity 23 A5 12 DQ4 13 daily DQ3 GND VBAT 22 A4 21 A3 14 DQ2 20 A2 Read and write access times as fast as 70ns 15 DQ1 19 16 A1 DQ0 Unlimited write cycle endurance 18 A0 17 GND Typical standby current 50 A 34-Pin PowerCap Module (PCM)