Digital Thermometer and Thermostat


The DS1621 Digital Thermometer and Thermostat provides 9-bit temperature readings, which indicate the temperature of the device. The thermal alarm output, TOUT is active when the temperature of the device exceeds a user-defined temperature TH. The output remains active until the temperature drops below user defined temperature TL, allowing for any hysteresis necessary. User-defined temperature settings are stored in nonvolatile memory so parts may be programmed prior to insertion in a system. Temperature settings and temperature readings are all communicated to/from the DS1621 over a simple 2-wire serial interface.
DS1621: Functional Block Diagram DS1621: Functional Block Diagram Enlarge+

Key Features

  • Simply Adds Temperature Monitoring and Control to Any System
    • Measures Temperatures From -55°C to +125°C in 0.5°C Increments. Fahrenheit Equivalent is -67°F to 257°F in 0.9°F Increments
    • Temperature is Read as a 9-Bit Value (2-Byte Transfer)
    • Converts Temperature to Digital Word in Less than 1s
    • Thermostatic Settings are User Definable And Nonvolatile
  • Can Be Used in a Wide Variety of Applications
    • Power Supply Range (2.7V to 5.5V)
    • Data is Read From/Written Via a 2-Wire Serial Interface (Open Drain I/O Lines)
  • Saves Space
    • Temperature Measurements Require No External Components
    • 8-pin DIP or SO package (208-mil) Packages


  • Medical
  • Networking
  • Personal Computing
  • Routers/Switches
  • Test Measurement Systems
  • Wireless Base Stations
Part Number Sensor Type Functions Interface Accuracy
Parasite Pwr. Temp. Thresh. Temp. Resolution
Multi Droppable Oper. Temp.
Package/Pins Budgetary
See Notes
DS1621  Local Single Temperature Alarm 2-Wire/I2C/SMBus 0.5 No Programmable (NV)
Yes -55 to +125
$2.13 @1k
See All Temperature Sensors (111)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Tools & Models

DS1621 IBIS Model

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