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