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

ƒ Unique 1-Wire® interface requires only one port pin for communication.

ƒ Each device has a unique 64-bit serial code stored in an on-board ROM.

ƒ Multidrop capability simplifies distributed temperature-sensing applications.

ƒ Requires no external components.

ƒ Can be powered from data line. Power supply range is 3.0V to 5.5V.

ƒ Measures temperatures from -55°C to +125°C (-67°F to +257°F).

ƒ ±2.0°C accuracy from -10°C to +85°C.

ƒ Thermometer resolution is user-selectable from 9 to 12 bits.

ƒ Converts temperature to 12-bit digital word in 750ms (max.)

ƒ User-definable nonvolatile (NV) alarm settings.

ƒ Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition).

ƒ Software compatible with the DS18B20.

ƒ Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermally sensitive system.