The DS1821 can function as a standalone thermostat with user-programmable trip-points or as 8-bit temperature sensor with a 1-Wire® digital interface. The thermostat trip-points are stored in nonvolatile memory, so DS1821 units can be programmed prior to system insertion for true standalone operation. The DS1821 has an operating temperature range of –55°C to +125°C and is accurate to ±1°C over a range of 0°C to +85°C. Communication with the DS1821 is accomplished through the open-drain DQ pin; this pin also serves as the thermostat output.

DS1821: Block Diagram

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Key Features

Requires no external components
Unique 1-Wire interface requires only one port pin for communication
Operates over a -55°C to +125°C (-67°F to +257°F) temperature range
Functions as a standalone thermostat with user-definable trip-points
Provides 8-bit (1°C resolution) centigrade temperature measurements
Accuracy is ±1°C over 0°C to +85°C range
Converts temperature to a digital word in 1 second (max)
Available in 3-pin TO92 and 8-pin SO packages
Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system

Applications/Uses

Consumer Products
Industrial Systems
Thermometers
Thermostatic Controls

Design Resources

Technical Documents

Reference Schematic 5508 Create a 1-Wire Master with Xilinx PicoBlaze
Tutorial 4679 Thermal Management Handbook
App Note 4600 Simple Software Validates the Hardware CRC and Detects Errors in the Serial Bit Stream of 1-Wire® Thermal Devices
App Note 3930 Package Thermal Resistance Values (Theta JA, Theta JC) for Temperature Sensors and 1-Wire Devices

Quality and Environmental Data

Product Reliability Reports: DS1821.pdf
Lead-Free Package Tin (Sn) Whisker Reports

Quality And Environmental

Device	Fab Process	Technology	Sample size	Rejects	FIT at 25°C	FIT at 55°C

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

Quality Management System >
Environmental Management System >

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Related Packaging

Technical Docs

Type	ID	Title
Reference Schematic	5508	Create a 1-Wire Master with Xilinx PicoBlaze
Tutorial	4679	Thermal Management Handbook
App Note	4600	Simple Software Validates the Hardware CRC and Detects Errors in the Serial Bit Stream of 1-Wire® Thermal Devices
App Note	3930	Package Thermal Resistance Values (Theta JA, Theta JC) for Temperature Sensors and 1-Wire Devices

Technical Docs

Reference Designs

Type	ID	Title
Reference Circuit	5508	Create a 1-Wire Master with Xilinx PicoBlaze

Reference Designs