Detailed Product Description

SPECIAL FEATURES
§ 1,152-bit secure read/write, nonvolatile
memory
§ Secure memory cannot be deciphered
without matching 64-bit password
§ Memory is partitioned into 3 blocks of 384
bits each
§ 64-bit password and ID fields for each
memory block
§ 512-bit scratchpad ensures data transfer
integrity
§ Operating temperature range: -40°C to
+70°C
§ Over 10 years of data retention
COMMON Button FEATURES
§ Unique, factory-lasered and tested 64-bit
registration number (8-bit family code + 48-
bit serial number + 8-bit CRC tester) assures
absolute traceability because no two parts are
alike
§ Multidrop controller for MicroBUS
§ Digital identification and information by
momentary contact
§ Chip-based data carrier compactly stores
information
§ Data can be accessed while affixed to object
§ Economically communicates to bus master
with a single digital signal at 16.3k bits per
second
§ Standard 16 mm diameter and 1-Bus
protocol ensure compatibility with Button
family
§ Button shape is self-aligning with cupshaped
probes
§ Durable stainless steel case engraved with
registration number withstands harsh
environments

The TM1991 MultiKey Button is a rugged read/write data carrier that acts as three separate electronic
keys, offering 1,152 bits of secure, nonvolatile memory. Each key is 384 bits long with distinct 64-bit
password and public ID fields (Figure 1). The password field must be matched in order to access the
secure memory. Data is transferred serially via the 1-Bus protocol, which requires only a single data lead
and a ground return. The 512-bit scratchpad serves to ensure integrity of data transfers to secure memory.
Data should first be written to the scratchpad where it can be read back. After the data has been verified, a
copy scratchpad command will transfer the data to the secure memory. This process ensures data integrity
when modifying the memory. A 48-bit serial number is factory lasered into each TM1991 to provide a
guaranteed unique identity which allows for absolute traceability. The family code for the TM1991 is 02h.
The durable MicroCan package is highly resistant to environmental hazards such as dirt, moisture and
shock. Its compact button-shaped profile is self-aligning with mating receptacles, allowing the TM1991 to
be easily used by human operators. Accessories permit the TM1991 to be mounted on plastic key fobs,
photo-ID badges, printed-circuit boards or any smooth surface of an object. Applications include secure
access control, debit tokens, work-in-progress tracking, electronic travelers and proprietary data.