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FEATURES
?  Requires no external components
?  Unique 1-Wire
?/DIV>
interface requires only one
port pin for communication
?  Operates over a -55癈 to +125癈 (-67癋 to
+257癋) temperature range
?  Functions as a standalone thermostat with
user-definable trip-points
?  Provides 8-bit (1癈 resolution) centigrade
temperature measurements
?  Accuracy is ?癈 over 0癈 to +85癈 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
PIN ASSIGNMENT
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癈 to +125癈 and is accurate to ?癈 over a range
of 0癈 to +85癈. Communication with the DS1821 is accomplished through the open-drain DQ pin; this
pin also serves as the thermostat output.
DS1821
Programmable Digital Thermostat and Thermometer
8-pin 208-mil SO
D  1  21
1
B  TT  M   IE
2 3
DS1821
1     
2   3
TO92
(DS1821C)
6
3
1
2
4
7
5
D
NC
V
N
NC
1-Wire is a registered trademark of Maxim Integrated
Products, Inc.
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