DS1621
PRELIMINARY
DS1621
Digital Thermometer and Thermostat
FEATURES
PIN ASSIGNMENT
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A0
A1
A2
•
Temperature measurements require no external com-
ponents
•
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 (two byte trans-
fer)
DS1621S
8–PIN SOIC (150 MIL)
See Mech. Drawings
Section
•
Converts temperature to digital word in 1 second
•
Thermostatic settings are user definable and nonvol-
atile
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A0
A1
A2
•
Data is read from/written via a 2–wire serial interface
(open drain I/O lines)
•
Applications include thermostatic controls, industrial
systems, consumer products, thermometers, or any
thermal sensitive system.
DS1621
8–PIN DIP (300 MIL)
See Mech. Drawings
Section
•
8–pin DIP or SOIC package
PIN DESCRIPTION
SDA
SCL
GND
T
OUT
A0
A1
A2
V
DD
–
–
–
–
–
–
–
–
2–Wire Serial Data Input/Output
2–Wire Serial Clock
Ground
Thermostat Output Signal
Chip Address Input
Chip Address Input
Chip Address Input
Power Supply Voltage
DESCRIPTION
The DS1621 digital thermometer and thermostat pro-
vides 9–bit temperature readings which indicate the
temperature of the device. 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 drops below user
defined temperature TL, allowing for any hysteresis
necessary.
User defined temperature settings are stored in non–
volatile memory, so parts may be programmed prior to
insertion in a system. Temperature settings, and tem-
perature readings are all communicated to/from the
DS1621 over a simple 2–wire serial interface.
ECopyright
1995 by Dallas Semiconductor Corporation.
All Rights Reserved. For important information regarding
patents and other intellectual property rights, please refer to
Dallas Semiconductor data books.
021497 1/14
ETC [ ETC ]
