DS1821 Datasheet, PDF (1/16 Pages) Dallas Semiconductor – Programmable Digital Thermostat

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DS1821
Programmable Digital Thermostat
FEATURES
Requires no external components
Measures temperatures from -55°C to +125°C
in 1°C increments. Fahrenheit equivalent is -
67°F to +257°F in 1.8°F increments DS1821
Converts temperature to digital word in 1
second (max.)
Thermostatic settings are user definable and
nonvolatile
Available in 3-pin PR35, TO-220, and 8-pin
SOIC packages
Applications include thermostatic controls,
industrial systems, consumer products,
thermometers, or any thermally sensitive
system
PIN ASSIGNMENT
DS1821
PR35 PACKAGE
See Mech. Drawing
Section
DS1821T
TO-220 PACKAGE
See Mech. Drawing
Section
DQ
1
8
V_DD
GND
2
7
NC
NC
3
6
NC
DNC
4
5
DNC
DS1821S 8-Pin SOIC (208-mil)
See Mech Drawings Section
PIN DESCRIPTION
GND
- Ground
DQ
- Data In/Out
V_DD
- Power Supply Voltage +5V
NC
- No Connect
DNC
- Do Not Connect
DESCRIPTION
The DS1821 Programmable Digital Thermostat provides a thermal alarm logic output 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 can be programmed prior to
insertion in a system. Communication to/from the DS1821 is accomplished through the DQ pin in a
programming mode; this same pin is used in operation as the thermostat output.
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