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DS1731 Schematic ( PDF Datasheet ) - Maxim Integrated

Teilenummer DS1731
Beschreibung High-Precision Digital Thermometer and Thermostat
Hersteller Maxim Integrated
Logo Maxim Integrated Logo 




Gesamt 14 Seiten
DS1731 Datasheet, Funktion
DS1631/DS1631A/
DS1731
High-Precision Digital
Thermometer and Thermostat
General Description
The DS1631, DS1631A, and DS1731 digital thermome-
ters 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 ≤ VDD ≤ 5.5V, and the DS1731 accuracy is ±1°C
from -10°C to +85°C with 3.0V ≤ VDD ≤ 5.5V. The ther-
mostat on all three devices provides custom hysteresis
with user-defined trip points (TH and TL). The TH and
TL 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.
Pin descriptions for the DS1631/DS1631A/DS1731 are pro-
vided in Table 2 and user-accessible registers are summa-
rized in Table 3. A functional diagram is shown in Figure 1.
Applications
● Network Routers and Switches
● Cellular Base Stations
● Portable Products
● Any Space-Constrained Thermally Sensitive Product
Benefits and Features
● Maximize System Accuracy in Broad Range of
Thermal Management Applications
• Operating Temperature Range: -55°C to +125°C
(-67°F to +257°F)
• DS1631 and DS1631A: ±0.5°C Accuracy over 0°C
to +70°C Range
• DS1731: ±1°C Accuracy over a -10°C to +85°C Range
• User-Selectable Output Resolution from 9 Bits to
12 Bits
● Reduce Cost with No External Components
● Simplify Distributed Temperature-Sensing Applications
with Multidrop Capability
• Up to Eight Devices Can Operate on a 2-Wire Bus
● Flexible and Nonvolatile User-Defined Thermostatic
Modes with Custom Hysteresis
● Available in 8-Pin µSOP and SO (DS1631 and
DS1631A Only) and the 8-Pin DIP (DS1631 Only)
Packages
Pin Configurations
TOP VIEW
SDA 1
SCL 2
TOUT 3
GND 4
+
DS1631
8 VDD
7 A0
6 A1
5 A2
µSOP
(DS1631U+, DS1631AU+, DS1731U+)
SDA 1 +
8 VDD
SCL 2
DS1631
7 A0
TOUT 3
6 A1
GND 4
5 A2
SO (150mil and 208mil)
(DS1631Z+, DS1631S+)
Ordering Information appears at end of data sheet.
See Table 2 for Pin Descriptions.
19-7488; Rev 1; 1/15






DS1731 Datasheet, Funktion
DS1631/DS1631A/
DS1731
High-Precision Digital
Thermometer and Thermostat
Operation—Measuring Temperature
The DS1631, DS1631A, and DS1731 measure tempera-
ture using bandgap-based temperature sensors. A delta-
sigma analog-to-digital converter (ADC) converts the
measured temperature to a 9-, 10-, 11-, or 12-bit (user-
selectable) digital value that is calibrated in °C; for °F
applications a lookup table or conversion routine must be
used. Throughout this data sheet, the term “conversion” is
used to refer to the entire temperature measurement and
ADC sequence.
The DS1631 and DS1731 always power-up in a low-pow-
er idle state, and the Start Convert T command must be
used to initiate conversions. The DS1631A begins conver-
sions automatically at power-up in the mode determined
by the configuration register’s 1SHOT bit.
The DS1631, DS1631A, and DS1731 can be programmed
to perform continuous consecutive conversions (continu-
ous-conversion mode) or to perform single conversions
on command (one-shot mode). The conversion mode is
programmed through the 1SHOT bit in the configuration
register as explained in the Configuration Register sec-
tion of this data sheet. In continuous-conversion mode,
the DS1631A begins performing continuous conversions
immediately at power-up, and the DS1631 and DS1731
begin continuous conversions after a Start Convert T
command is issued. For all three devices, consecu-
tive conversions continue to be performed until a Stop
Convert T command is issued, at which time the device
goes into a low-power idle state. Continuous conversions
can be restarted at any time using the Start Convert T
command.
In one-shot mode the DS1631A performs a single con-
version at power-up, and the DS1631 and DS1731
perform a single temperature conversion when a Start
Convert T command is issued. For all three devices,
when the conversion is complete the device enters a
low-power idle state and remains in that state until a
single temperature conversion is again initiated by a Start
Convert T command.
The resolution of the output digital temperature data is
user-configurable to 9, 10, 11, or 12 bits, corresponding
to temperature increments of 0.5°C, 0.25°C, 0.125°C, and
0.0625°C, respectively. The default resolution at power-
up is 12 bits, and it can be changed through the R0 and
R1 bits in the configuration register. Note that the conver-
sion time doubles for each additional bit of resolution.
After each conversion, the digital temperature is stored
as a 16-bit two’s complement number in the two-byte
temperature register as shown in Figure 4. The sign bit
(S) indicates if the temperature is positive or negative:
for positive numbers S = 0 and for negative numbers
S = 1. The Read Temperature command provides user
access to the temperature register. Bits 3 through 0 of
the temperature register are hardwired to 0. When the
device is configured for 12-bit resolution, the 12 MSbs
(bits 15 through 4) of the temperature register contain
temperature data. For 11 bit resolution, the 11 MSbs (bits
15 through 5) of the temperature register contain data,
and bit 4 is 0. Likewise, for 10-bit resolution, the 10 MSbs
(bits 15 through 6) contain data, and for 9-bit the 9 MSbs
(bits 15 through 7) contain data, and all unused LSbs con-
tain 0s. Table 4 gives examples of 12-bit resolution output
data and the corresponding temperatures.
Table 4. 12-Bit Resolution Temperature/
Data Relationship
TEMPERATURE
(°C)
+125
+25.0625
+10.125
+0.5
0
-0.5
-10.125
-25.0625
-55
DIGITAL OUTPUT
(BINARY)
0111 1101 0000 0000
0001 1001 0001 0000
0000 1010 0010 0000
0000 0000 1000 0000
0000 0000 0000 0000
1111 1111 1000 0000
1111 0101 1110 0000
1110 0110 1111 0000
1100 1001 0000 0000
DIGITAL
OUTPUT (HEX)
7D00h
1910h
0A20h
0080h
0000h
FF80h
F5E0h
E6F0h
C900h
MS BYTE
LS BYTE
BIT 15
S
BIT 7
2-1
BIT 14
26
BIT 6
2-2
BIT 13
25
BIT 5
2-3
Figure 4. Temperature, TH, And TL Register Format
BIT 12
24
BIT 4
2-4
BIT 11
23
BIT 3
0
BIT 10
22
BIT 2
0
BIT 9
21
BIT 1
0
BIT 8
20
BIT 0
0
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DS1731 pdf, datenblatt
DS1631/DS1631A/
DS1731
High-Precision Digital
Thermometer and Thermostat
Operation Example
In this example, the master configures the DS1631/DS1631A/DS1731 (A1A2A3 = 000) for continuous conversions and
thermostatic function.
MASTER THERMETER*
DATA
MODE
MODE
(MSB FIRST)
COMMENTS
TX RX START START condition from MASTER.
TX RX
90h MASTER sends control byte with R/W = 0.
RX TX
ACK
Acknowledge bit from THERMOMETER.
TX RX
ACh
MASTER sends Access Config command.
RX TX
ACK
Acknowledge bit from THERMOMETER.
TX RX
RX TX
02h
ACK
MASTER writes a data byte to the configuration register to put the THERMOMETER
in continuous conversion mode and set the TOUT polarity to active high.
Acknowledge bit from THERMOMETER.
TX RX
STOP
STOP condition from MASTER.
TX RX START START condition from MASTER.
TX RX
RX TX
90h
ACK
MASTER sends control byte with R/W = 0.
Acknowledge bit from THERMOMETER.
TX RX
A1h MASTER sends Access TH command.
RX TX
ACK
Acknowledge bit from THERMOMETER.
TX RX
RX TX
28h
ACK
MASTER sends most significant data byte for TH = +40°C.
Acknowledge bit from THERMOMETER.
TX RX
RX TX
00h
ACK
MASTER sends least significant data byte for TH = +40°C.
Acknowledge bit from THERMOMETER.
TX RX
STOP
STOP condition from MASTER.
TX RX START START condition from MASTER.
TX RX
RX TX
90h
ACK
MASTER sends control byte with R/W = 0.
Acknowledge bit from THERMOMETER.
TX RX
A2h MASTER sends Access TL command.
RX TX
ACK
Acknowledge bit from THERMOMETER.
TX RX
RX TX
0Ah
ACK
MASTER sends most significant data byte for TL = +10°C.
Acknowledge bit from THERMOMETER.
TX RX
RX TX
00h
ACK
MASTER sends least significant data byte for TL = +10°C.
Acknowledge bit from THERMOMETER.
TX RX
STOP
STOP condition from MASTER.
TX RX START START condition from MASTER.
TX RX
RX TX
90h
ACK
MASTER sends control byte with R/W = 0.
Acknowledge bit from THERMOMETER.
TX RX
51h MASTER sends Start Convert T command.
RX TX
ACK
Acknowledge bit from THERMOMETER.
TX RX
STOP
STOP condition from MASTER.
*THERMOMETER = DS1631, DS1631A, or DS1731
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