1
of
18
071107
ma
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 PR35 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°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.
DS1821
Programmable Digital Thermostat and
Thermometer
8-pin 208-mil SO
(DS1821S)
1
(BOTTOM VIEW)
2 3
DALLAS
DS1821
1
GND
DQ
V
DD
2 3
PR35
(DS1821)
6
3
1
2
4
8
7
5
DQ
GND
NC
NC
V
DD
NC
NC
NC
DS182
1S
1-Wire is a registered trademark of Dallas Semiconductor Corp.,
a wholly owned subsidiary of Maxim Integrated Products, Inc.
www.maxim-ic.com
