General Description
The DS1990R serial number iButton® is a rugged data carrier that serves as an electronic registration number for automatic identification. Data is transferred serially through the 1-Wire® protocol, which requires only a single data lead and a ground return. Every DS1990R is factory lasered with a guaranteed unique 64-bit registration number that allows for absolute traceability. The durable stainless-steel iButton 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 DS1990R to be used easily by human operators. Accessories enable the DS1990R iButton to be mounted on almost any object, including containers, pallets, and bags.
The DS1990R is a fully compatible variant of the DS1990A. In applications where a presence pulse on contact is critical, the DS1990R should be preferred over the DS1990A.

Features
♦ Upgrade of DS1990A Guarantees Presence Pulse on Contact
♦ Can Be Read in Less Than 5ms
♦ Operating Range: 2.8V to 6.0V, -40°C to +85°C

Common iButton Features
♦ Unique Factory-Lasered 64-Bit Registration Number Ensures Error-Free Device Selection and Absolute Traceability Because No Two Parts are Alike
♦ Built-In Multidrop Controller for 1-Wire Net
♦ Digital Identification by Momentary Contact
♦ Data Can Be Accessed While Affixed to Object
♦ Economically Communicates to Bus Master with a Single Digital Signal at 16.3kbps
♦ Button Shape is Self-Aligning with Cup-Shaped 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

Applications
   Access Control
   Work-In-Progress Tracking
   Tool Management
   Inventory Control