DESCRIPTION
The DS1251 4096K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 512K words by 8 bits) with a built-in real-time clock. The DS1251Y has a self-contained lithium energy source and control circuitry, which 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 garbled data in both the memory and real-time clock.

FEATURES
■ Real-Time Clock Keeps Track of Hundredths Of Seconds, Minutes, Hours, Days, Date of the Month, Months, and Years
■ 512K x 8 NV SRAM Directly Replaces Volatile Static RAM or EEPROM
■ Embedded Lithium Energy Cell Maintains Calendar Operation and Retains RAM Data
■ Watch Function is Transparent to RAM Operation
■ Automatic Leap Year Compensation Valid Up to 2100
■ Over 10 Years of Data Retention in the Absence of Power
■ Full 10% Operating Range
■ Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time
■ DIP Module Only
    – Standard 32-Pin JEDEC Pinout
    – Upward Compatible with the DS1248
■ PowerCap Module Board Only
    − Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal
    − Replaceable Battery (PowerCap)
    − Pin-for-Pin Compatible with Other Densities of DS124xP Phantom Clocks
■ Underwriters Laboratories (UL) Recognized (www.maxim-ic.com/qa/info/ul/)