DS1822 Datasheet

• Unique 1-Wire^® Interface Requires Only One Port Pin for Communications
  • Can Be Powered from Data Line
  • Power-Supply Range is 3.0V to 5.5V
• Reduced Component Count with Integrated Temperature Sensor and Interface
  • Requires No External Components
  • Measures temperatures from -55°C to +125°C (-67°F to +257°F)
  • ±2.0°C Accuracy from -10°C to +85°C
  • Thermometer Resolution is User-Selectable from 9 to 12 Bits
  • Converts Temperature to 12-Bit Digital Word in 750ms (max)
• Simplifies Distributed Temperature Sensing with Multidrop Capability
  • Each Device Has a Unique 64-Bit Serial Code Stored in an On-Board Device
  • Flexible, User-Definable Nonvolatile (NV) Alarm Settings with Alarm Search Command Identifies Devices with Temperatures Outside Programmed Limits
  • Software compatible with the DS18B20
• Applications Include Thermostatic Controls, Industrial Systems, Consumer Products, Thermometers, or Any Thermally Sensitive System

• Fire Alarm Systems
• Hard Disk Drive
• Storage Area Networks (SANs)
• Telecommunications

The DS1822 is a digital thermometer with ±2°C accuracy over a -10°C to +85°C range. Data is read out over a 1-Wire® serial bus in 2's complement format with 9 to 12 bits of resolution (user-programmable).

The DS1822 offers thermostatic functionality with over-temperature (T_H) and under-temperature (T_L) user-programmable setpoints stored in on-chip EEPROM. An internal flag is set when the measured temperature is greater than T_H or less than T_L. If thermostatic operation is not required, the two bytes of EEPROM reserved for T_H and T_L may be used for general-purpose nonvolatile storage.

Each DS1822 features a unique and unchangeable 64-bit silicon serial number, which serves as the bus address for the sensor. This allows multiple DS1822 devices to coexist on the same 1-Wire bus. The DS1822 may be locally powered via a 3.0V to 5.5V supply, or power can be derived from the 1-Wire data line ("parasite power").

The DS1822 is offered in 3-pin TO-92 (DS1822) and 150mil 8-pin SO (DS1822Z) packages. In addition, the DS1822 is available in a parasite-power only version, the DS1822-PAR. Also available is the high-precision DS18B20, which provides ±0.5°C accuracy and is software-compatible with the DS1822.