DS1720
PRELIMINARY
DS1720
Econo – Digital Thermometer and
Thermostat
FEATURES
PIN ASSIGNMENT
DQ
CLK/CONV
RST
GND
1
2
3
4
8
7
6
5
V
DD
T
HIGH
T
LOW
T
COM
•
Requires no external components
•
Supply voltage range covers from 2.7V to 5.5V
•
Measures
temperatures from –55°C to +125°C in
0.5°C increments. Fahrenheit equivalent is –67°F to
+257°F in 0.9°F increments
•
Temperature is read as a 9–bit value
•
Converts
(max)
temperature to digital word in 1 second
DQ
CLK/CONV
DS1720S 8–PIN SOIC (208 MIL)
See Mech Drawings Section
PIN DESCRIPTION
– 3–Wire Input/Output
– 3–Wire Clock Input and
Stand–alone
Convert Input
– 3–Wire Reset Input
– Ground
– High Temperature Trigger
– Low Temperature Trigger
– High/Low Combination Trigger
– Power Supply Voltage (3V – 5V)
•
Thermostatic settings are user–definable and non–
volatile
•
Data is read from/written via a 3–wire serial interface
(CLK, DQ, RST)
•
Applications include thermostatic controls, industrial
systems, consumer products, thermometers, or any
thermally sensitive system
•
8–pin SOIC (208 mil) package
RST
GND
T
HIGH
T
LOW
T
COM
V
DD
DESCRIPTION
The DS1720 Digital Thermometer and Thermostat pro-
vides 9–bit temperature readings which indicate the
temperature of the device. With three thermal alarm out-
puts, the DS1720 can also act as a thermostat. T
HIGH
is
driven high if the DS1720’s temperature is greater than
or equal to a user–defined temperature TH. T
LOW
is
driven high if the DS1720’s temperature is less than or
equal to a user–defined temperature TL. T
COM
is driven
high when the temperature exceeds TH and stays high
until the temperature falls below that of TL.
User–defined temperature settings are stored in non–
volatile memory, so parts can be programmed prior to
insertion in a system, as well as used in stand–alone
applications without a CPU. Temperature settings and
temperature readings are all communicated to/from the
DS1720 over a simple 3–wire interface.
030598 1/12
DALLAS [ DALLAS SEMICONDUCTOR ]
