The iButton®1Kb/4Kb memory (DS1992) is a rugged read/write data carrier that act 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 device is attached. Data is transferred serially through the 1-Wire®protocol that requires only a single data lead and a ground return.The scratchpad is an additional page that acts as a buffer when writing to memory. Data is first written to the scratchpad where it can be read back. After the data has been verified, a copy scratchpad command transfers the data to memory. This process ensures data integrity when modifying the memory. A 48-bit serial number is factory lasered into each DS199_ to provide a guaranteed unique identity that allows for absolute traceability. The durable MicroCan®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 DS199_ to be easily used by human operators. Accessories permit the DS199_ to be mounted on almost any surface including plastic key fobs, photo-ID badges, and PC boards. Applications include access control, work-in-progress tracking, electronic travelers, storage of calibration constants, and debit tokens.ApplicationsDebit TokensElectronic TravelersStorage of Calibration ConstantsWork-in-Progress Tracking