DS1554

19-5497; Rev 9/10 www.maxim-ic.com DS1554 256k, Nonvolatile, Y2K-Compliant Timekeeping RAM FEATURES  Integrated NV SRAM, Real-Time Clock (RTC), Crystal, Power-Fail Control Circuit, and Lithium Energy Source  Clock Registers are Accessed Identically to the Static RAM; These Registers Reside in the 16 Top RAM Locations  Century Byte Register (i.e., Y2K Compliant)  Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power  Precision Power-On Reset  Programmable Watchdog Timer and RTC Alarm  BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic LeapYear Compensation Valid Up to the Year 2100  Battery Voltage-Level Indicator Flag  Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance  Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time  Also Available in Industrial Temperature Range: -40°C to +85°C PIN CONFIGURATIONS TOP VIEW RST N.C. A14 A12 A7 A6 A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND 1 32 2 Maxim 31 3 DS1554 30 4 29 5 28 6 27 7 26 8 25 9 24 10 23 11 22 12 21 13 20 14 19 15 18 16 17 VCC N.C. IRQ/FT WE A13 A8 A9 A11 OE A10 CE DQ7 DQ6 DQ5 DQ4 DQ3 Encapsulated DIP IRQ/FT N.C. N.C. RST VCC WE OE CE DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0 GND 1 34 2 Maxim 33 3 4 DS1554 32 31 5 30 6 29 7 28 8 27 9 26 10 25 11 24 12 23 13 22 14 21 15 20 16 19 17 X1 GND VBAT X2 18 N.C. N.C. A14 A13 A12 A11 A10 A9 A8...