Rainbow Electronics DS1821 - Manual

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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 SOIC
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
PRELIMINARY
www.dalsemi.com
8-pin 208-mil SOIC
(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
DS18
21
S