256k NV SRAM with Phantom Clock

Please check latest availability status for a specific part variant.


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.

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 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

See parametric specs for Timekeeping & Real-Time Clocks (78)

Part NumberInterfaceVSUPPLY
Memory TypeMemory Size
Time of Day AlarmsFunctionsPackage/PinsBudgetary
See Notes
Phantom Clock
$17.61 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: DS1244.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >


Related Resources

±5ppm, I2C Real-Time Clock with Integrated MEMS Oscillator

  • Highly Accurate RTC with Integrated MEMS Resonator Completely Manages All Timekeeping Functions
  • 64-Byte RAM for User Data Storage
  • Simple Serial Interface Connects to Most Microcontrollers