DS18B20

Programmable Resolution 1-Wire Digital Thermometer

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
• ±0.5°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 Programmed Limits (Temperature Alarm Condition) ƒ

• Available in 8-Pin SO (150 mils), 8-Pin μSOP, and 3-Pin TO-92 Packages
• Software Compatible with the DS1822
• ƒApplications Include Thermostatic Controls, Industrial Systems, Consumer Products, Thermometers, or Any Thermally Sensitive System

DESCRIPTION

The DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user-programmable upper and lower trigger points. The DS18B20 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 ±0.5°C over the range of -10°C to +85°C. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.

Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s 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.

ABSOLUTE MAXIMUM RATINGS

Voltage Range on Any Pin Relative to Ground .................................................................-0.5V to +6.0V

Operating Temperature Range......................................................................................-55°C to +125°C

Storage Temperature Range ........................................................................................-55°C to +125°C

Solder Temperature ....................................................Refer to the IPC/JEDEC J-STD-020 Specification.

These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

PIN CONFIGURATIONS

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