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FEATURES
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
μSOP Packages and the DS1631 is Also
Available in a 150mil SO package—see
Table 1 for Ordering Information
PIN CONFIGURATIONS
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.
DS1631/DS1631A/DS1731
High-Precision Digital
Thermometer and Thermostat
www.maxim-ic.com
SO (150mil and 208mil)
(DS1631Z+, DS1631S+)
L
V
DD
A
0
A
1
A
2
GND
T
OUT
D
6
7
3
2
SOP
(DS1631U+, DS1631AU+,
DS1731U+)
L
V
DD
A
0
A
1
A
2
GND
T
OUT
D
6
7
3
2
See Table 2 for Pin Descriptions
APPLICATIONS
Network Routers and Switches
Cellular Base Stations
Portable Products
Any Space-Constrained Thermally Sensitive
Product
