DESCRIPTION

The DS1244 256K NV SRAM with a Phantom clock is a fully static nonvolatile RAM (NV SRAM) (organized as 32K words by 8 bits) with a built-in real-time clock. The DS1244 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 (RTC) Keeps Track of Hundredths of Seconds, Minutes, Hours, Days, Date of the Month, Months, and Years

■ 32K 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

■ Full 10 Operating Range

■ Over 10 Years of Data Retention in the Absence of Power

■ Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time

■ DIP Module Only

■ Standard 28-Pin JEDEC Pinout

■ PowerCap Module Board Only

    – Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal

    – Replaceable Battery (PowerCap)

    – Pin-for-Pin Compatible with DS1248P and DS1251P

■ Underwriters Laboratories (UL) Recognized