General Description
The DS1990A 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 DS1990A has a 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 DS1990A to be used easily
by human operators. Accessories enable the DS1990A
iButton to be mounted on almost any object, including containers,
pallets, and bags.

Features
● Can Be Read in Less Than 5ms
Common iButton Features
● Unique 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

Applications
● Access Control
● Work-in-Progress Tracking
● Tool Management
● Inventory Control