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DS1994
4Kb Plus Time Memory iButton®


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Status
Part Number Status Replacement Explanation
DS1994 This product is Not Recommended for New Designs. See Ordering Information for recommended replacements. DS1904 DS1994 is only available under allocation due to end of life program. Recommended alternative will require software/firmware updates to existing systems.

Data Sheet
FULL DATA SHEET (PDF, 732kB)
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Description
The DS1994 Memory iButton is a rugged read/write data carrier that acts as a localized database, easily accessible with minimal hardware. The nonvolatile memory and optional timekeeping capability offer a simple solution to storing and retrieving vital information pertaining to the object to which the iButton is attached. Data is transferred serially through the 1-Wire® protocol that requires only a single data lead and a ground return.

The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written to the scratchpad where it can be read back. After the data has been verified, a copy scratchpad command transfers the data to memory. This process ensures data integrity when modifying the memory. A 48-bit serial number is factory lasered into each DS1994 to provide a guaranteed unique identity that allows for absolute traceability. The durable MicroCan package is highly resistant to environmental hazards such as dirt, moisture, and shock. Its compact, coin-shaped profile is self-aligning with mating receptacles, allowing the DS1994 to be easily used by human operators. Accessories permit the DS1994 to be mounted on almost any surface including plastic key fobs, photo-ID badges, and PC boards.

The DS1994 also includes time-keeping functions, a real-time clock/calendar, interval timer, cycle counter, and programmable interrupts, in addition to the nonvolatile memory. The internal clock can be programmed to deny memory access based on absolute time/date, total elapsed time, or the number of accesses. These features allow the DS1994 to be used to create a stopwatch, alarm clock, time and date stamp, logbook, hour meter, calendar, system power cycle timer, interval timer, and event scheduler.

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

Key Features
  • 4096 bits of Read/Write Nonvolatile Memory
  • 256-bit Scratchpad Ensures Integrity of Data Transfer
  • Memory Partitioned into 256-bit Pages for Packetizing Data
  • Data Integrity Assured with Strict Read/Write Protocols
  • Contains Real-Time Clock/Calendar in Binary Format
  • Interval Timer Can Automatically Accumulate Time When Power is Applied
  • Programmable Cycle Counter can Accumulate the Number of System Power-On/Off Cycles
  • Programmable Alarms Can Be Set to Generate Interrupts for Interval Timer, Real-Time Clock, and/or Cycle Counter
  • Write-Protect Feature Provides Tamperproof Time Data
  • Programmable Expiration Date That Limits Access to SRAM and Timekeeping
  • Clock Accuracy is Better Than ±2 Minutes/Month at 25°C
  • Operating Temperature Range from -40°C to +70°C
  • Over 10 Years of Data Retention
  • Underwriters Laboratories (UL®) Recognized

Diagram

Application Notes
  • Application Note 74: Reading and Writing 1-Wire® Devices Through Serial Interfaces - DS1994
  • Application Note 155: 1-Wire® Software Resource Guide Device Description - DS1994
  • Application Note 244: Advanced 1-Wire Network Driver - DS1994
  • Application Note 937: Book of iButton® Standards - DS1994

    Design Guides
  • Real-Time Clocks (PDF)
  • 1-Wire® Products (PDF)

    Reliability Reports
  • Reliability Report: DS1994.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: 1-2 of 2

    DS1994 Notes Free
    Sample
    Buy Status Recommended Replacement
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    DS1994L-F5   F5 MicroCan  
    NRND DS1994L-F5+
    CAN-F5;2 pin;301 mm²
    Outline Drawing: 21-0266 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: IB-5CW*
    0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    DS1994L-F5+    
    NRND DS1904
    CAN-F5;2 pin;301 mm²
    Outline Drawing: 21-0266 (PDF)
    Land Pattern: Not Available
    Use pkgcode/variation: IB+5CW*
    0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis

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    2008-07-23
    This page last modified: 2008-07-23


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