The document describes a product with a 1,152-bit secure read/write nonvolatile memory and a 64-bit password. The memory is partitioned into 3 blocks, each with a 64-bit password and ID fields. The product also features a 512-bit scratchpad for data transfer integrity. It operates in a temperature range of -40°C to +70°C and has over 10 years of data retention.
The DS1991 MultiKey iButton is a rugged, secure read/write data carrier that provides three separate 384‑bit subkeys with 64‑bit passwords and a 512‑bit scratchpad for data integrity.
This handbook describes the device’s special features, memory architecture, 1‑Wire command set, hardware configuration, and physical and electrical specifications.
| Secure memory size | 1,152 bits |
|---|---|
| Scratchpad size | 512 bits |
| Memory blocks | 3 blocks of 384 bits each |
| Operating temperature | -40°C to +70°C |
| Expected service life | 10 years at 25°C |
| Weight | 3.3 grams |
| Voltage rating (any pin) | -0.5V to +7.0V |
| Data rate | 16.3 kbits per second |
The DS1991 is accessed via a single data line using the 1‑Wire protocol.
The device’s memory is partitioned into three blocks of 384 bits each.
It operates from –40 °C to +70 °C.