Automatic Information
iButton Products

Contents: DS1994 Memory + Time iButton DS1963S Monetary iButton DS1920 Temperature iButton DS1921 Thermochron iButton UniqueWare Devices

DS1994 Memory Plus Time iButton Features: Smallest real time clock and memory module with over 10 years of permanent operation Interval timer can automatically accumulate time when power is applied Programmable cycle counter can accumulate the number of system power-on/off cycles Programmable alarms can be set to generate interrupts for interval timer, real time clock, and/or cycle counter Write protect feature provides tamper-proof time data Programmable expiration date limits access to SRAM and timekeeping Clock accuracy is better than ±2 minutes/month at 25°C The DS1994 Memory Plus Time iButton is a rugged read/write data carrier that acts as a localized database that can be easily accessed with minimal hardware. The nonvolatile memory and timekeeping capability offers a simple solution to storing and retrieving vital information pertaining to the object to which the iButton is attached. Data is transferred serially via the 1-Wire™ protocol which requires only a single data line and a ground return.

Applications:

• Stopwatch, alarm clock, calendar
• Time and date stamping of events
• Run time meter (power cycles, hours) for equipment
• Time-restricted access control
• Expiration controller for leased equipment
• Interval timer, event scheduler for maintenance

Related Information: Automatic Information application notes, technical briefs and articles, standards, and related articles

DS1963S 4Kbit Monetary iButton with SHA-1 Function

Features:

• 4096 bits of read/write nonvolatile memory
• Eight 32-bit, read-only non rolling-over page write cycle counters
• Eight 64-bit write-only secrets with associated secrets write cycle counters
• On-chip 512-bit SHA-1 engine to compute 160-bit Message Authentication Codes
• Device can operate as a roaming iButton or as a coprocessor for a host computer
• Can support multiple services
• Can be used to authenticate host or as a user iButton
• Overdrive mode boosts communication speed to 142k bits per second
• Data integrity assured with strict read/write protocols
• On-chip 16-bit CRC generator to safeguard data read operation
• Over 10 years of data retention

The DS1963S Monetary iButton with SHA-1 Function can store data which represents money. Challenge and Response Authentication positively identifies a device as belonging to an application without exposing any secret information. The monetary data itself is protected by means of an SHA-1 message authentication code, which links it to a particular device, secret and memory page, preventing unauthorized refilling of purses. Up to seven independent change purses or services can be randomly accessed from the on-chip directory. Each Monetary Transaction (write cycle) generates a unique number to audit the dispensing and refilling of purses. A change purse can be decremented with less than 100ms touch time for rapid processing in crowded public facilities.

Applications:

• Electronic purse with transaction counter
  • vending machines
  • public transportation systems
  • amusement parks
  • integrated solution for access control and monetary transactions in hotels
• High-security access control
  • door access control
  • computer and other equipment usage control
  • secured Internet/Intranet access control and remote authentication
• Tamper-proof electronic data carrier

Related Information: Automatic Information application notes, technical briefs and articles, standards, and related articles

"Secure Hash Standard"

DS1920 Temperature iButton

• Digital thermometer measures temperatures from -55°C to +100°C, typically in 0.2 seconds
• Accuracy ±0.5°C within 0°C to +70°C, no calibration or reference required
• Zero standby power
• Power supply through data contact
• Access to internal counters allows increased resolution through interpolation
• Two bytes of EEPROM for use as alarm triggers or user memory
• Built-in network controller supports alarm search to directly identify devices sensing alarming temperatures
• Device-generated 8-bit CRC for on-the-fly data integrity check

The DS1920 Temperature iButton provides 9-bit temperature readings which indicate the temperature of the device. Information is sent to/from the DS1920 over a 1-Wire interface. Power for reading, writing, and performing temperature conversions is derived from the data line itself. Because each DS1920 contains a unique silicon serial number, multiple DS1920s can exist on the same 1-Wire bus. This allows placement of temperature sensors in many different locations and obtaining an entire temperature profile of a room, building, piece of equipment, etc. rather than just a few discrete points.

Applications:

• HVAC environmental controls
• Thermostatic controls
• Sensing temperature in buildings, equipment, or machinery
• In-process thermal monitoring and control
• Thermodynamic research of temperature profiles
• Fire alarm and sprinkler systems

Related Information: Automatic Information application notes, technical briefs and articles, standards, and related articles

DS1921 Thermochron iButton

• Digital thermometer measures temperatures from -40°C to +85°C in 0.5°C increments
• Accuracy ±1°C from -20°C to 70°C
• Logs up to 2048 consecutive temperature measurements in read-only nonvolatile memory
• Automatically wakes up and measures temperature at user-specified intervals from 1 to 255 minutes
• Programmable high and low temperature alarm trip points
• Records time stamp and duration when temperature exceeded the specified high and low range
• Records a temperature histogram in 63 bins with a 2°C resolution
• Y2K-compliant real time clock accuracy ±2 minutes/month from 0°C to 45°C
• 4096-bit general purpose read/write nonvolatile memory
• Overdrive mode boosts communication speed to 142k bits per second
• Data integrity assured with strict read/write protocols
• On-chip 16-bit CRC generator to safeguard data read operation

The DS1921 Thermochron iButton is a revolutionary, small, temperature recording device. It incorporates a direct-to-digital temperature sensor, a Y2K-compliant realtime clock/calendar, and nonvolatile memory into a 16 mm stainless steel iButton enclosure. The DS1921K Thermochron iButton Starter Kit contains all of the hardware necessary to configure a Thermochron iButton and review the resulting data. The data can also be saved or imported into other applications.

Applications:

• Tracking and recording of temperature-sensitive foods and products during shipping
• Sense and record temperature history of equipment and environment
• HVAC environment and thermostatic controls
• In-process thermal monitoring and control
• Thermodynamic research of temperature profile
• Fire alarm and sprinkler systems

Related Information: Automatic Information application notes, technical briefs and articles, standards, and related articles

UniqueWare™ Devices

• 1-Wire EPROM is factory programmed and serialized according to customer-supplied information and then write-protected
• Dallas Semiconductor handles serialization and bookkeeping for tracking the last number used
• Up to 121 bytes of user-defined information, including serialization
• Customer-specific project ID number together with custom ROM for highest level of product security
• Programmed devices are made available only to the owner of the project ID or their authorized agents
• Minimum order size of 1,000 pieces; no NRE charge, short lead time
• Wide operating voltage range (2.8V to 6.0V) and industrial temperature range (-40°C to +85°C)
• Available as DS2502-UNW, DS2505-UNW and DS2506-UNW Silicon Label and DS1982U, DS1985U and DS1986U UniqueWare iButton

Applications:

• After-market protection of products by restricted availability
• Node ID chip for network cards (IEEE-assigned number)
• Wireless phone ID plus battery information
• Electronic product identification label with serialization

Additional information:

• UniqueWare software options and data structure: Application Note 99, "UniqueWare Project Setup Manual"
• UniqueWare Project Setup Software is available from our FTP Site at ftp://ftp.dalsemi.com/pub/auto_id/, file name unwsetup.exe.