DESCRIPTION

The DS18S20-PAR digital thermometer provides 9–bit centigrade temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18S20-PAR does not need an external power supply because it derives power directly from the data line (“parasite power”). The DS18S20-PAR communicates over a 1-wire bus, which 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 +100°C and is accurate to ±0.5°C over a range of –10°C to +85°C.

Each DS18S20-PAR has a unique 64-bit identification code, which allows multiple DS18S20-PARs to function on the same 1–wire bus; thus, it is simple to use one microprocessor to control many DS18S20-PARs distributed over a large area. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems inside buildings, equipment or machinery, and process monitoring and control systems.

FEATURES

• Unique 1-wire interface requires only one port pin for communication

• Derives power from data line (“parasite power”)—does not need a local power supply

• Multi-drop capability simplifies distributed temperature sensing applications

• Requires no external components

• ±0.5°C accuracy from –10°C to +85°C

• Measures temperatures from –55°C to +100°C (–67°F to +212°F)

• 9-bit thermometer resolution

• Converts temperature in 750 ms (max.)

• User–definable non-volatile temperature alarm settings

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

• Ideal for use in remote sensing applications (e.g., temperature probes) that do not have a local power source