iButton 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. COMMON iButton FEATURES ■ Unique, Factory-Lasered, and Tested 64-bit Registration Number (8-bit Family Code + 48-bit Serial Number + 8-bit CRC Tester) Assures Absolute Traceability Because No Two Parts Are Alike ■ Multidrop Controller for 1-Wire Network ■ Digital Identification and Information by Momentary Contact ■ Chip-Based Data Carrier Compactly Stores Information ■ Data Can Be Accessed While Affixed to Object ■ Economically Communicates to Bus Master with a Single Digital Signal at 16.3kbps ■ Standard 16mm Diameter and 1-Wire® Protocol Ensure Compatibility with iButton Family ■ Button Shape is Self-Aligning with CupShaped Probes ■ Durable Stainless Steel Case Engraved with Registration Number Withstands Harsh Environments ■ Easily Affixed with Self-Stick Adhesive Backing, Latched by its Flange, or Locked with a Ring Pressed onto its Rim ■ Presence Detector Acknowledges when Reader First Applies Voltage ■ Meets UL#913 (4th Edit.); Intrinsically Safe Apparatus, Approved under Entity Concept for Use in Class I, Division 1, Group A, B, C and D Locations SPECIAL 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
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