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Maxim > Products > [Real-Time Clocks] 
DS1244, DS1244P
256k NV SRAM with Phantom Clock


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Status
Part Number Status
DS1244 Active: In Production. But some versions of the family are No Longer Available. See Ordering Information.
DS1244P Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 356kB)
Download this datasheet in PDF formatDownload   Send this datasheet to any email addressE-Mail

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.

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.

This product contains lithium-metal batteries. See applicable regulations for transport requirements for batteries in equipment.

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
  • Month and Year Determine the Number of Days in Each Month; Valid Up to 2100
  • Full 10% Operating Range
  • Operating Temperature Range: 0°C to +70°C
  • 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
  • Underwriters Laboratories (UL®) Recognized

Key Specifications:  Timekeeping & Real-Time Clocks
Part Number Date/ Time Format Interface VSUPPLY
(V)		 Memory Type Memory Size
(Bytes)		 Time of Day Alarms Price
hh = sec/100 See Notes
DS1244  YY-MM-DD/ HH:MM:SS:hh
Bytewide
Phantom Clock
3.3
5
 NV SRAM 32K 0 $13.10 @1k
See All Timekeeping & Real-Time Clocks (80)

Diagram
DS1244, DS1244P: Typical Operating Circuit
Typical Operating Circuit

Application Notes
  		• Application Note 52: Using the Dallas Phantom Real-Time Clocks (RTCs) - DS1244P
  		• Application Note 504: Design Considerations for Dallas Semiconductor Real-Time Clocks - DS1244
  		• Application Note 507: PowerCap Package Allows for Density Upgrades, Surface Mount Assembly - DS1244
  		• Application Note 509: Using the SmartWatch/Phantom Clocks with a Microcontroller - DS1244

    Design Guides
  		• Real-Time Clocks (PDF)

    Reliability Reports
  		• Reliability Report: DS1244.pdf DS1244P.pdf
  		• Underwriters Laboratories (UL®) Recognized

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-9 of 9

    DS1244 Free
    Sample    		 Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    DS1244W-120     N/A No Longer Available DS1244W-120+
    		 EDIP;28 pin;630 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT28-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1244Y-70     N/A No Longer Available DS1244Y-70+
    		 EDIP;28 pin;630 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT28-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1244W-120+  
    		Active
    		EDIP;28 pin;630 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT28+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1244Y-70+  
    		Active
    		EDIP;28 pin;630 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT28+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1244W-120IND+    
    		Active
    		EDIP;28 pin;630 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT28+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1244WP-120     N/A No Longer Available
    		PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1244WP-120+  
    		Active
    		PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1244YP-70+  
    		Active
    		PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1244WP-120IND+    
    		Active
    		PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    Related Products
    DS9034PCX PowerCap with Crystal

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    2005-07-08
    This page last modified: 2009-10-26


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