Dallas DS1820 Instruction

FEATURES
TM
Unique 1–Wire 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
Temperature is read as a 9–bit digital value.
Converts temperature to digital word in 200 ms (typ.)
User–definable, nonvolatile temperature alarm set-
tings
Alarm search command identifies and addresses
devices whose temperature is outside of pro-
grammed limits (temperature alarm condition)
Applications include thermostatic controls, industrial
systems, consumer products, thermometers, or any
thermally sensitive system
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.
Copyright 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.
TM
1–Wire Digital Thermometer
PIN ASSIGNMENT
DALLAS DALLAS
DS2434
DS1820
1
BOTTOM VIEW
1 2 3
1
NC
NC 2
NC 3
NC 4
NC 5
NC 6
VDD 7
DQ 8
DS1820
PR35 PACKAGE
See Mech. Drawings See Mech. Drawings
Section
PIN DESCRIPTION
GND – Ground
DQ – Data In/Out
V – Optional V
DD DD
NC – No Connect
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.
DS1820
DS1820
2 3
16 NC
15 NC
14 NC
13 NC
12 NC
11 NC
10 NC
9 GND
DS1820S
16–PIN SSOP
Section
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