DS1631/DS1631A/DS1731
High-Precision Digital
Thermometer and Thermostat
www.maxim-ic.com
FEATURES
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DS1631 and DS1631A Provide
±0.5°C
Accuracy over a 0°C to +70°C Range
DS1731 Provides
±1°C
Accuracy over a
-10°C to +85°C Range
DS1631A Automatically Begins Taking
Temperature Measurements at Power-Up
Operating Temperature Range: -55°C to
+125°C (-67°F to +257°F)
Temperature Measurements Require No
External Components
Output Resolution is User-Selectable to 9,
10, 11, or 12 Bits
Wide Power-Supply Range (+2.7V to +5.5V)
Converts Temperature-to-Digital Word in
750ms (max)
Multidrop Capability Simplifies Distributed
Temperature-Sensing Applications
Thermostatic Settings are User-Definable
and Nonvolatile (NV)
Data is Read/Written Through 2-Wire Serial
Interface (SDA and SCL Pins)
All Three Devices are Available in 8-Pin
mSOP
Packages and the DS1631 is Also
Available in a 150mil SO package—see
Table 1 for Ordering Information
PIN CONFIGURATIONS
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A
0
A
1
A
2
mSOP
(DS1631U, DS1631AU, DS1731U)
SDA
SCL
T
OUT
GND
1
2
3
4
8
7
6
5
V
DD
A
0
A
1
A
2
SO (150mil)
(DS1631Z)
See Table 2 for Pin Descriptions
APPLICATIONS
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Network Routers and Switches
Cellular Base Stations
Portable Products
Any Space-Constrained Thermally Sensitive
Product
DESCRIPTION
The DS1631, DS1631A, and DS1731 digital thermometers provide 9, 10, 11, or 12-bit temperature
readings over a -55°C to +125°C range. The DS1631 and DS1631A thermometer accuracy is
±0.5°C
from 0°C to +70°C with 3.0V
£
V
DD
£
5.5V, and the DS1731 accuracy is
±1°C
from -10°C to +85°C with
3.0V
£
V
DD
£
5.5V. The thermostat on all three devices provides custom hysteresis with user-defined trip
points (T
H
and T
L
). The T
H
and T
L
registers and thermometer configuration settings are stored in NV
EEPROM so they can be programmed prior to installation. In addition, the DS1631A automatically
begins taking temperature measurements at power-up, which allows it to function as a stand-alone
thermostat. Communication with the DS1631/DS1631A/DS1731 is achieved through a 2-wire serial
interface, and three address pins allow up to eight devices to be multidropped on the same 2-wire bus.
Pin descriptions for the DS1631/DS1631A/DS1731 are provided in Table 2 and user-accessible registers
are summarized in Table 3. A functional diagram is shown in Figure 1.
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092502
DS1631/DS1631A/DS1731
Table 1. ORDERING INFORMATION
ORDERING
NUMBER
DS1631U
DS1631U/T&R
DS1631Z
DS1631Z/T&R
DS1631AU
DS1631AU/T&R
DS1731U
DS1731U/T&R
PACKAGE
MARKING
D1631
D1631
DS1631Z
DS1631Z
1631A
1631A
D1731
D1731
DESCRIPTION
DS1631 in 8-Pin
mSOP
DS1631 in 8-Pin
mSOP,
3000-Piece Tape-and-Reel
DS1631 in 150mil 8-Pin SO
DS1631 in 150mil 8-Pin SO, 2500-Piece Tape-and-Reel
DS1631A in 8-Pin
mSOP
DS1631A in 8-Pin
mSOP,
3000-Piece Tape-and-Reel
DS1731 in 8-Pin
mSOP
DS1731 in 8-Pin
mSOP,
3000-Piece Tape-and-Reel
Table 2. DETAILED PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
SYMBOL
SDA
SCL
T
OUT
GND
A
2
A
1
A
0
V
DD
DESCRIPTION
Data Input/Output Pin for 2-Wire Serial Communication Port. Open-Drain.
Clock Input Pin for 2-Wire Serial Communication Port.
Thermostat Output Pin. Push-Pull.
Ground Pin
Address Input Pin
Address Input Pin
Address Input Pin
Supply Voltage Pin. +2.7V to +5.5V Power-Supply Pin.
Figure 1. FUNCTIONAL DIAGRAM
V
DD
CONFIGURATION REGISTER
AND CONTROL LOGIC
TEMPERATURE SENSOR
and
DS
ADC
ADDRESS
AND
I/O CONTROL
SCL
SDA
A
0
A
1
A
2
TEMPERATURE REGISTER
T
H
REGISTER
DIGITAL
COMPARATOR/LOGIC
T
L
REGISTER
T
OUT
GND
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DS1631/DS1631A/DS1731
ABSOLUTE MAXIMUM RATINGS*
Voltage on any Pin Relative to Ground
Operating Temperature Range
Storage Temperature Range
Solder Dip Temperature (10s)
Reflow Oven Temperature
-0.5V
to +6.0V
-55°C to +125°C
-55°C to +125°C
See IPC/JEDEC J-STD-020A Specification
+220°C
*
These are stress ratings only and functional operation of the device at these or any other conditions
above those indicated in the operation sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods of time may affect reliability.
DC ELECTRICAL CHARACTERISTICS
(V
DD
= 2.7V to 5.5V; T
A
= -55°C to +125°C.)
PARAMETER
Supply Voltage
DS1631, DS1631A
Thermometer Error
SYMBOL
V
DD
T
ERR
CONDITION
0°C to +70°C,
3.0V
£
V
DD
£
5.5V
0°C to +70°C,
2.7V
£
V
DD
<
3.0V
-55°C to +125°C
-10°C to +85°C,
3.0V
£
V
DD
£
5.5V
-10°C to +85°C,
2.7V
£
V
DD
<
3.0V
-55°C to +125°C
-0.5
0.7 x
V
DD
0
0
-10
MIN
2.7
MAX
5.5
±0.5
±1
±2
±1
±1.5
±2
0.3 x V
DD
V
DD
+ 0.3
0.4
0.6
+10
1
mA
1.25
400
110
800
2.4
0.4
µA
nA
V
V
4
1
1
3
V
V
V
µA
°C
2
°C
2
UNITS
V
NOTES
1
DS1731
Thermometer Error
Low-Level Input
Voltage
High-Level Input
Voltage
SDA Low-Level
Output Voltage
Input Current Each
I/O Pin
T
ERR
V
IL
V
IH
V
OL1
V
OL2
3mA sink current
6mA sink current
0.4 < V
I/O
< 0.9V
DD
Temperature
conversion
-55°C to +85°C
Temperature
conversion
+85°C to +125°C
E
2
write
Communication only
0°C to +70°C
1mA source current
4mA sink current
Active Supply
Current
I
DD
Standby Supply
Current
T
OUT
Output Logic
Voltage
I
STBY
V
OH
V
OL
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Embedded System
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