DS1921G		Thermochron iButton Device
General Description
The Thermochron® iButton® device (DS1921G) is a rugged, self-sufficient system that measures temperature
and records the result in a protected memory section. The recording is done at a user-defined rate, both as
a direct storage of temperature values as well as in the form of a histogram. Up to 2048 temperature values
taken at equidistant intervals ranging from 1 to 255 min can be stored. The histogram provides 63 data bins
with a resolution of 2.0°C. If the temperature leaves a user-programmable range, the DS1921G also records
when this happened, for how long the temperature stayed outside the permitted range, and if the temperature
was too high or too low. An additional 512 bytes of battery-backed SRAM allow storing information pertaining
to the object to which the DS1921G is associated. Data is transferred serially through the 1-Wire® protocol, which
requires only a single data lead and a ground return. Every DS1921G is factory lasered with a guaranteed unique,
electrically readable, 64-bit registration number that allows for absolute traceability. The durable stainless steel
package is highly resistant to environmental hazards such as dirt, moisture, and shock. Accessories permit the
DS1921G to be mounted on almost any object including containers, pallets, and bags.
Applications
Temperature Logging in Cold Chain, Food Safety, Pharmaceutical, and Medical Products
Benefits and Features
§  High Accuracy, Full-Featured Digital Temperature Logger Simplifies Temperature Data Collection and
Dissemination of Electronic Temperature Record
-   Accuracy +/-1°C from -30°C to +70°C (See the Electrical Characteristics for Accuracy Specification)
-   Digital Thermometer Measures Temperature in 0.5°C Increments
-   Built-In Real-Time Clock (RTC) and Timer Has Accuracy of +/-2 Minutes per Month from 0°C to +45°C
-   Automatically Wakes Up and Measures Temperature at User-Programmable Intervals from 1 Minute to 255 Minutes
-   Logs Consecutive Temperature Measurements in 2kB of Datalog Memory
-   Records a Long-Term Temperature Histogram with 2.0°C Resolution
-   Programmable Temperature High and Temperature Low Alarm Trip Points
-   Records Up to 24 Timestamps and Durations When Temperature Leaves the Range Specified by the Trip Points
-   Individually Calibrated in a NIST-Traceable Chamber
-   Complies to Standard EN12830
-   512 Bytes of General-Purpose Battery-Backed SRAM
§  Rugged Construction Survives Harsh Environments
-   Water Resistant Enclosure (IP56) or Waterproof if Placed Inside DS9107 iButton Capsule (Exceeds Water Resistant
3 ATM Requirements)
-  CE, FCC, and UL913 Certifications
§  Simple Serial Port Interfaces to Most Microcontrollers for Rapid Data Transfer
-  Communicates to Host with a Single Digital Signal Up to 15.4kbps at Standard Speed or Up to 125kbps in
overdrive Mode Using 1-Wire Protocol
Absolute Maximum Ratings
IO Voltage Range Relative to GND	-0.5V to +6V
IO Sink Current	20mA
Operating Temperature Range	-40°C to +85°C*
Storage Temperature Range	-40°C to +50°C*
* Storage or operation above +50°C significantly reduces battery life.