iButton DS1990AF5 — Readonly electronic identification key Key benefits Provides a permanent, factorylasered unique ID for reliable device or user identification. Simple, plugandplay operation with 1Wire/iButton readers — no batteries or configuration required. Durable stainlesssteel package designed for repeated physical contact and long service life. Prevents duplication and simplifies authentication, access control, and asset tracking workflows. What it does Supplies a fixed, unchangeable 64bit ROM identification number (unique serial) that can be read by standard iButton/1Wire readers. Functions as a contactbased electronic key for identification and authentication tasks. Passive device: powered only while in contact with a reader, so no maintenance or battery replacement is needed. Compatibility and interface Model: DS1990AF5 (Maxim/Dallas iButton family). Communicates over the industrystandard 1Wire/iButton interface. Works with common iButton readers and probes (for example, desktop or handheld iButton readers and contact probes) that support DS1990A devices. Physical attributes and performance Encapsulated in a stainlesssteel iButton housing for mechanical protection and reliable electrical contact. Compact, coinlike form factor designed to mate with standard iButton readers. Factorylasered serial ensures a consistent, tamperresistant identifier; robust for frequent reads in industrial or pointofservice environments. Practical applications (examples) Access control: use as a physical key for door entry systems, turnstiles, or secured equipment where a simple, durable identifier is required. Asset and inventory tagging: attach to tools, equipment, or components to record presence and provenance when scanned by compatible readers. User identification and time logging: employ as a convenient, maintenance token for employee time clocks, machine logins, or shared resource signon. Why choose DS1990AF5 Straightforward deployment with existing 1Wire/iButton infrastructure. Lowmaintenance, longlived identification token suited to industrial, commercial, and service environments. Recognized, standardized model from the Maxim/Dallas iButton family for predictable compatibility. Ordering reference Model number: DS1990AF5 (readonly iButton with factorylasered unique 64bit ROM).