DS1820
1–Wire
TM
DS1820
Digital Thermometer
FEATURES
PIN ASSIGNMENT
DALLAS
DALLAS
DS2434
DS1820
1
2
3
•
Unique 1–Wire
TM
interface requires only one port pin
for communication
•
Multidrop capability simplifies distributed temperature
sensing applications
•
Requires no external components
•
Can be powered from data line
•
Zero standby power required
•
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
BOTTOM VIEW
1
2 3
•
Temperature is read as a 9–bit digital value.
•
Converts temperature to digital word in 200 ms (typ.)
•
User–definable,
tings
nonvolatile temperature alarm set-
DS1820
PR35 PACKAGE
See Mech. Drawings
Section
GND
DQ
VDD
NC
NC
NC
NC
NC
NC
VDD
DQ
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
NC
NC
NC
NC
NC
NC
GND
DS1820S
16–PIN SSOP
See Mech. Drawings
Section
•
Alarm
search command identifies and addresses
devices whose temperature is outside of pro-
grammed limits (temperature alarm condition)
systems, consumer products, thermometers, or any
thermally sensitive system
PIN DESCRIPTION
GND
DQ
V
DD
NC
–
–
–
–
Ground
Data In/Out
Optional V
DD
No Connect
•
Applications include thermostatic controls, industrial
DESCRIPTION
The DS1820 Digital Thermometer provides 9–bit tem-
perature readings which indicate the temperature of the
device.
Information is sent to/from the DS1820 over a 1–Wire
interface, so that only one wire (and ground) needs to be
connected from a central microprocessor to a DS1820.
Power for reading, writing, and performing temperature
conversions can be derived from the data line itself with
no need for an external power source.
Because each DS1820 contains a unique silicon serial
number, multiple DS1820s can exist on the same
1–Wire bus. This allows for placing temperature sen-
sors in many different places. Applications where this
feature is useful include HVAC environmental controls,
sensing temperatures inside buildings, equipment or
machinery, and in process monitoring and control.
030598 1/27
DALLAS [ DALLAS SEMICONDUCTOR ]
