DS1821 Datasheet, PDF (1/19 Pages) Dallas Semiconductor – Programmable Digital Thermostat

19-6322; Rev 6/12
DS1821
Programmable Digital Thermostat and Thermometer
FEATURES
 Requires no external components
 Unique 1-Wire^® interface requires only one
port pin for communication
 Operates over a -55°C to +125°C (-67°F to
+257°F) temperature range
 Functions as a standalone thermostat with
user-definable trip-points
 Provides 8-bit (1°C resolution) centigrade
temperature measurements
 Accuracy is ±1°C over 0°C to +85°C range
 Converts temperature to a digital word in
1 second (max)
 Available in 3-pin TO92 and 8-pin SO
packages
 Applications include thermostatic controls,
industrial systems, consumer products,
thermometers, or any thermally sensitive
system
1-Wire is a registered trademark of Maxim Integrated
Products, Inc.
PIN ASSIGNMENT
DS1821
12 3
DQ 1
GND ²
NC 3
NC ⁴
8
V_DD
7 _NC
6 _NC
5 _NC
8-pin 208-mil SO
(DS1821S)
12 3
(BOTTOM VIEW)
TO92
(DS1821C)
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.
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