DS1621
Digital Thermometer and Thermostat
www.dalsemi.com
FEATURES
§
Temperature measurements require no
external components
§
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 (2-
byte transfer)
§
Wide power supply range (2.7V to 5.5V)
§
Converts temperature to digital word in 1
second
§
Thermostatic settings are user definable
and nonvolatile
§
Data is read from/written via a two–wire
serial interface (open drain I/O lines)
§
Applications include thermostatic
controls, industrial systems, consumer
products, thermometers, or any thermal
sensitive system
§
8–pin DIP or SOIC package (150-MIL and
208-MIL)
PIN ASSIGNMENT
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A
0
A
1
A
2
DS1621S 8-PIN SOIC (150-MIL)
DS1621V 8-PIN SOIC (208-MIL)
See Mech Drawings Section
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A
0
A
1
A
2
DS1621 8-PIN DIP (300-MIL)
See Mech Drawings Section
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 provides 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 nonvolatile memory so parts may be programmed prior to
insertion in a system. Temperature settings and temperature readings are all communicated to/from the
DS1621 over a simple two–wire serial interface.
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DALLAS [ DALLAS SEMICONDUCTOR ]
