Ds18b20

DS18B20 Programmable Resolution 1-Wire Digital Thermometer
www.maxim-ic.com

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 to5.5V Measures Temperatures from -55°C to +125°C (-67°F to +257°F) ±0.5°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 Programmed Limits (Temperature Alarm Condition)Available in 8-Pin SO (150 mils), 8-Pin μSOP, and 3-Pin TO-92 Packages Software Compatible with the DS1822 Applications Include Thermostatic Controls, Industrial Systems, Consumer Products, Thermometers, or Any Thermally Sensitive System
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PIN CONFIGURATIONS
DALLAS 18B20 1 2 3 VDD DQ
3 4

N.C. N.C.

1

8

N.C. N.C. N.C. GND

DALLAS 18B20

2

7 6 5

SO (150 mils) (DS18B20Z)GND DQ VDD

DQ N.C. N.C. GND

1 2 3 4

8 7 6 5

VDD N.C. N.C. N.C.

1 2

3

μSOP (DS18B20U)

18B20

(BOTTOM VIEW)

TO-92 (DS18B20)

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 bydefinition 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 serialcode, 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.
1-Wire is a registeredtrademark of Maxim Integrated Products, Inc.

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REV: 042208

DS18B20

ORDERING INFORMATION
PART DS18B20 DS18B20+ DS18B20/T&R DS18B20+T&R DS18B20-SL/T&R DS18B20-SL+T&R DS18B20U DS18B20U+ DS18B20U/T&R DS18B20U+T&R DS18B20Z DS18B20Z+ DS18B20Z/T&R DS18B20Z+T&R TEMP RANGE -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C-55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C -55°C to +125°C PIN-PACKAGE 3 TO-92 3 TO-92 3 TO-92 (2000 Piece) 3 TO-92 (2000 Piece) 3 TO-92 (2000 Piece)* 3 TO-92 (2000 Piece)* 8 μSOP 8 μSOP 8 μSOP (3000 Piece) 8 μSOP (3000 Piece) 8 SO 8 SO 8 SO (2500 Piece) 8 SO (2500 Piece) TOP MARK 18B20 18B20 18B20 18B20 18B20 18B20 18B20 18B20 18B20 18B20 DS18B20DS18B20 DS18B20 DS18B20

+Denotes a lead-free package. A “+” will appear on the top mark of lead-free packages. T&R = Tape and reel. *TO-92 packages in tape and reel can be ordered with straight or formed leads. Choose “SL” for straight leads. Bulk TO-92 orders are straight leads only.

PIN DESCRIPTION
PIN SO 1, 2, 6, 7, 8 3 4 5 μSOP 2, 3, 5, 6, 7 8 1 4 TO-92 — 3 2 1 NAME N.C. VDD DQ GND NoConnection Optional VDD. VDD must be grounded for operation in parasite power mode. Data Input/Output. Open-drain 1-Wire interface pin. Also provides power to the device when used in parasite power mode (see the Powering the DS18B20 section.) Ground FUNCTION

OVERVIEW
Figure 1 shows a block diagram of the DS18B20, and pin descriptions are given in the Pin Description table. The 64-bit ROM...