Rainbow Electronics DS1720 - Manual

DS1720
Econo – Digital Thermometer and
Thermostat
DS1720
PRELIMINARY
030598 1/12
FEATURES
•
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 temperature to digital word in 1 second
(max)
•
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
PIN ASSIGNMENT
GND
V DD
RST
CLK/CONV
DQ
T LOW
T HIGH
T COM
1
2
3
4
8
7
6
5
DS1720S 8–PIN SOIC (208 MIL)
See Mech Drawings Section
PIN DESCRIPTION
DQ – 3–Wire Input/Output
CLK/CONV – 3–Wire Clock Input and
Stand–alone
Convert Input
RST – 3–Wire Reset Input
GND – Ground
T
HIGH
– High Temperature Trigger
T
LOW
– Low Temperature Trigger
T
COM
– High/Low Combination Trigger
V
DD
– Power Supply Voltage (3V – 5V)
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.