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FEATURES
§ Temperature measurements require no
external components with ±1°C accuracy
§ Measures temperatures from -55°C to
+125°C; Fahrenheit equivalent is -67°F to
+257°F
§ Temperature resolution is configurable from 9
to 12 (default) bits (0.5°C to 0.0625°C
resolution)
§ Maximum conversion time (9-bit resolution)
of 93.75 ms
§ Thermostatic settings are user-definable
§ Data is read/written via a 2-wire serial
interface (open drain I/O lines); 3-bit
addressability
§ Wide power supply range (2.7V - 5.5V)
§ Applications include personal computers,
cellular telephones, office equipment, or any
thermally sensitive system
§ 8-pin, 150-mil SOIC package and 8-pin µSOP
package
PIN ASSIGNMENT
PIN DESCRIPTION
SDA - 2-Wire Serial Data Input/Output
SCL - 2-Wire Serial Clock
GND - Ground
T
OUT
- Thermostat Output Signal
A
0
- Chip Address Input
A
1
- Chip Address Input
A
2
- Chip Address Input
V
DD
- Power Supply Voltage (+5V)
DESCRIPTION
The DS1721 2-Wire Digital Thermometer and Thermostat provides 12-bit temperature readings, which
indicate the temperature of the device. Thermostatic settings and temperature readings are all
communicated to/from the DS1721 over a simple 2-wire serial interface. No additional components are
required; the device is truly a “temperature-to-digital” converter.
The DS1721 has three address bits that allow a user to multidrop up to eight sensors along the 2-wire bus,
greatly simplifying the bussing of distributed temperature sensing networks.
The thermal alarm output, T
OUT
, is active when the temperature of the device exceeds a user-defined
temperature TH. The output remains active until the temperature is equal to or below the user-defined
temperature TL, allowing for any hysteresis necessary. The active state of T
OUT
is configurable by the
user.
For applications that require faster conversion times, the user can adjust the readout resolution from 12 to
9 bits, effectively reducing the conversion time from 750ms (MAX) to 93.75 ms (MAX). This is
particularly useful in applications where temperature changes large magnitudes very rapidly.
Applications for DS1721 include personal computers/services, cellular telephones, office equipment, or
any microprocessor-based, thermally sensitive system.
DS1721
2-Wire Digital Thermomete
and Thermostat
www.maxim-ic.com
*
DS1721U
8-Pin µ-SOP
V
DD
A
0
A
1
A
2
SD
SCL
T
OUT
GND
1
2 7
4
DS1721S
8-Pin SOIC (150-mil)
SD
SCL
T
OUT
GND
V
DD
A
0
A
1
A
2
