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DS1647, DS1647P
Nonvolatile Timekeeping RAM


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Status
Part Number Status
DS1647 Active: In Production. But some versions of the family are No Longer Available. See Ordering Information.
DS1647P Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 196kB)
Download this datasheet in PDF formatDownload   Send this datasheet to any email addressE-Mail


Description
The DS1647 is a 512k x 8 nonvolatile static RAM with a full-function real-time clock, which are both accessible in a byte-wide format. The nonvolatile timekeeping RAM is functionally equivalent to any JEDEC standard 512k x 8 SRAM. The device can also be easily substituted for ROM, EPROM and EEPROM, providing read/write nonvolatility and the addition of the real-time clock function. The real-time clock information resides in the eight uppermost RAM locations. The RTC registers contain year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for the day of the month and leap year are made automatically. The RTC clock registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1647 also contains its own power-fail circuitry, which deselects the device when the VCC supply is in an out-of-tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.

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

Key Features
  • Integrates NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source
  • Clock Registers Are Accessed Identically to the Static RAM. These Registers are Resident in the Eight Top RAM Locations.
  • Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
  • BCD Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Leap Year Compensation Valid Through 2099
  • Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance
  • DS1647 Only (DIP Module):
    • Standard JEDEC Byte-Wide 128k x 8 RAM Pinout
  • DS1647P Only (PowerCap Module Board):
    • Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal
    • Replaceable Battery (PowerCap)
    • Power-Fail Output
    • Pin-for-Pin Compatible with Other Densities of DS164xP Timekeeping RAM
  • Underwriters Laboratories (UL®) Recognized

Diagram
DS1647, DS1647P: Block Diagram
Block Diagram

Application Notes
  • Application Note 504: Design Considerations for Dallas Semiconductor Real-Time Clocks - DS1647
  • Application Note 507: PowerCap Package Allows for Density Upgrades, Surface Mount Assembly - DS1647
  • Application Note 519: Using a Nonvolatile Timekeeping RAM with a Microcontroller - DS1647

    Design Guides
  • Real-Time Clocks (PDF)

    Reliability Reports
  • Reliability Report: DS1647.pdf DS1647P.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: 1-4 of 4

    DS1647 Notes Free
    Sample
    Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    DS1647-120     N/A No Longer Available DS1647-120+
    EDIP;32 pin;707 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT32-4*
    0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1647-120+  
    Active
    EDIP;32 pin;707 mm²
    Outline Drawing: 21-0245 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: MDT32+4*
    0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    DS1647P Notes Free
    Sample
    Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    DS1647P-120   120ns  
    Active
    PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2-1*
    0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1647P-120+  
    Active
    PCAP;34 pin;597 mm²
    Outline Drawing: 21-0246 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: PC2+1*
    0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    Related Products
    DS9034PCX PowerCap with Crystal

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    2006-11-30
    This page last modified: 2009-09-24


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