ma
DS1821
Programmable Digital Thermostat and
Thermometer
www.maxim-ic.com
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
DQ
DALLAS
1
8
V
DD
NC
NC
NC
DS1821S
DS1821
1 2 3
GND
NC
NC
2
3
4
7
6
5
8-pin 208-mil SO
(DS1821S)
(BOTTOM VIEW)
PR35
(DS1821)
PIN DESCRIPTION
GND
DQ
V
DD
NC
- Ground
- Data In/Out and Thermostat Output
- Power Supply Voltage
- No Connect
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.
1 of 18
071107
DESCRIPTION
GND
DQ
V
DD
1 2
3
DALLAS [ DALLAS SEMICONDUCTOR ]
