256k NV SRAM with Phantom Clock

 

Part Number	Replacement	Explanation

Description

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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 V_CC 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.

The phantom clock provides timekeeping information for hundredths of seconds, seconds, minutes, hours, days, date, months, and years. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The phantom clock operates in either 24-hour or 12-hour format with an AM/PM indicator.

DS1244, DS1244P: Typical Operating Circuit Enlarge+

Key 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
• Available in Lead-Free Package