Introduces the characteristics of 1152-bit secure read/write, nonvolatile memory, which cannot be deciphered unless 64-bit password matches. The memory is partitioned into 3 blocks of 384 bits each, each memory block has 64-bit password and ID fields, 512-bit scratchpad ensures data transfer integrity, the operating temperature range is -40°C to +70°C, and the data retention time is over 10 years.
The DS1991 MultiKey iButton is a rugged, stainless‑steel data carrier that provides three independent 384‑bit secure memory blocks, each protected by a 64‑bit password and ID. It communicates over a single‑wire 1‑Wire bus, allowing simple connection to micro‑controllers or PCs.
The handbook details the device’s special features, command structure, memory function commands, 1‑Wire bus timing, hardware configuration, and full electrical and mechanical specifications, enabling developers to integrate the iButton into access‑control, token, and data‑logging applications.
| Operating temperature range | -40°C to +70°C |
|---|---|
| Weight | 3.3 grams |
| Expected service life | 10 years at 25 °C |
| Voltage on any pin (relative to ground) | -0.5 V to +7.0 V |
| Input Logic Low (VIL) | -0.3 V |
| Pull‑up resistor (recommended) | ≈5 kΩ for short lines |
Data is first written to the 512‑bit scratchpad, verified, and then transferred to secure memory with the Copy Scratchpad command.
A pull‑up resistor of about 5 kΩ is recommended for short bus lengths.
The device operates from –40 °C up to +70 °C.