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 to 5.5V
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
®
PIN CONFIGURATIONS
DALLAS
18B20
1 2 3
V
DD
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
V
DD
DQ
N.C.
N.C.
GND
1
2
3
4
8
7
6
5
V
DD
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 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.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
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REV: 042208
DALLAS [ DALLAS SEMICONDUCTOR ]
