DS18B20
Programmable Resolution
1-Wire Digital Thermometer
www.maxim-ic.com
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DALLAS
18B20
NC
2
VDD
3
8
4
NC
7
NC
6
NC
5
1
DQ
1 2 3
NC
GND
8-Pin 150mil SO
(DS18B20Z)
1 2
3
DQ
NC
NC
GND
(BOTTOM VIEW)
1
2
3
4
18B20
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PIN ASSIGNMENT
DALLAS
18B20
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Unique 1-Wire® interface requires only one
port pin for communication
Each device has a unique 64-bit serial code
stored in an onboard 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 of programmed limits (temperature
alarm condition)
Available in 8-pin SO (150mil), 8-pin mSOP,
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
GND
DQ
VDD
FEATURES
8
VDD
7
NC
6
NC
5
NC
8-Pin mSOP
(DS18B20U)
TO-92
(DS18B20)
PIN DESCRIPTION
GND
DQ
VDD
NC
- Ground
- Data In/Out
- Power Supply Voltage
- No Connect
DESCRIPTION
The DS18B20 Digital Thermometer provides 9 to 12–bit centigrade 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 Dallas Semiconductor.
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