DESCRIPTION

The DS1822 digital thermometer provides 9- to 12-bit centigrade temperature measurements and has an alarm function with NV user-programmable upper and lower trigger points. The DS1822 communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. It has an operating temperature range of –55°C to +125°C and is accurate to ±2.0°C over the range of –10°C to +85°C. In addition, the DS1822 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.

FEATURES

■ Unique 1-Wire? interface requires only one

?? port pin for communication.

■ Each device has a unique 64-bit serial code

?? stored in an on-board ROM.

■ Multidrop capability simplifies distributed

?? temperature-sensing applications.

■ Requires no external components.

■ Can be powered from data line. Power supply

?? range is 3.0V to 5.5V.

■ 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.)

■ User-definable nonvolatile (NV) alarm

?? settings.

■ Alarm search command identifies and

?? addresses devices whose temperature is

?? outside of programmed limits (temperature

?? alarm condition).

■ Software compatible with the DS18B20.

■ Applications include thermostatic controls,

?? industrial systems, consumer products,

?? thermometers, or any thermally sensitive

?? system.