1 of 17 022103
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 2-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 SO package (150mil and
208mil)
PIN ASSIGNMENT
PIN DESCRIPTION
SDA - 2-Wire Serial Data Input/Output
SCL - 2-Wire Serial Clock
GND - Ground
T
OUT
- Thermostat Output Signal
A0 - Chip Address Input
A1 - Chip Address Input
A2 - Chip Address Input
V
DD
- 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 2-wire serial interface.
DS1621
Digital Thermometer and Thermostat
www.maxim-ic.com
6
3
1
2
4
8
7
5
SD
A
T
OUT
GND
V
DD
A
0
A
1
A
2
DS1621S 8-PIN SO (150mil)
DS1621V 8-PIN SO (208mil)
See Mech Drawings Section
6
3
1
2
4
8
7
5
SD
A
SCL
T
OUT
GND
V
DD
A
0
A
1
A
2
DS1621 8-PIN DIP (300mil)
See Mech Drawings Section
SCL
