DS1821_07 Datasheet, PDF (1/18 Pages) Dallas Semiconductor – Programmable Digital Thermostat and Thermometer

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DS1821
Programmable Digital Thermostat and
Thermometer
FEATURES
ƒ Requires no external components
ƒ Unique 1-Wire^® interface requires only one
port pin for communication
ƒ Operates over a -55°C to +125°C (-67°F to
+257°F) temperature range
ƒ Functions as a standalone thermostat with
user-definable trip-points
ƒ Provides 8-bit (1°C resolution) centigrade
temperature measurements
ƒ Accuracy is ±1°C over 0°C to +85°C range
ƒ Converts temperature to a digital word in 1
second (max)
ƒ Available in 3-pin PR35 and 8-pin SO
packages
ƒ Applications include thermostatic controls,
industrial systems, consumer products,
thermometers, or any thermally sensitive
system
PIN ASSIGNMENT
DALLAS
DS1821
12 3
DQ 1
GND ²
NC 3
NC ⁴
8 _VDD
7 _NC
6 _NC
5 _NC
8-pin 208-mil SO
(DS1821S)
12 3
(BOTTOM VIEW)
PR35
(DS1821)
PIN DESCRIPTION
GND - Ground
DQ - Data In/Out and Thermostat Output
V_DD - Power Supply Voltage
NC - No Connect
DESCRIPTION
The DS1821 can function as a standalone thermostat with user-programmable trip-points or as 8-bit
temperature sensor with a 1-Wire digital interface. The thermostat trip-points are stored in nonvolatile
memory, so DS1821 units can be programmed prior to system insertion for true standalone operation.
The DS1821 has an operating temperature range of –55°C to +125°C and is accurate to ±1°C over a range
of 0°C to +85°C. Communication with the DS1821 is accomplished through the open-drain DQ pin; this
pin also serves as the thermostat output.
1-Wire is a registered trademark of Dallas Semiconductor Corp.,
a wholly owned subsidiary of Maxim Integrated Products, Inc.
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