1990A SPECIAL FEATURES
 Upgrade of DS1990 allows multiple Serial Number iButtons to
reside on a common bus
 Unique 48bit serial number
 Low-cost electronic key for access control
 8-bit CRC for checking data integrity
 Can be read in less than 5 ms
 Operating temperature range of -40°C to +85°C
COMMON iButton FEATURES
 Unique, factory-lasered and tested 64-bit
registration number (8-bit family code + 48-
bit serial number + 8bit CRC tester) assures
absolute traceability because no two parts arealike.
 Multidrop controller for MicroLAN.
 Digital identification by momentary contact.
 Chip-based data carrier compactly stores information.
 Data can be accessed while affixed to an object.
 Economically communicates to bus master with a single digital signal at 16.3k bits per second.
 Standard 16 mm 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.