MAX31722_V01 [MAXIM]
Digital Thermometers and Thermostats with SPI/3-Wire Interface;
| 型号： | MAX31722_V01 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Digital Thermometers and Thermostats with SPI/3-Wire Interface |
| 文件： | 总15页 (文件大小：536K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
General Description
Benefits and Features
● Maximize System Accuracy in Broad Range of
Thermal Management Applications
The MAX31722/MAX31723 digital thermometers and
thermostats with an SPI/3-wire interface provide tem-
perature readings that indicate the device temperature.
No additional components are required; the devices
are truly temperature-to-digital converters. Temperature
readings are communicated from the device over an
SPI interface or a 3-wire serial interface. The choice of
interface is selectable by the user. For applications that
require greater temperature resolution, the user can
adjust the readout resolution from 9 to 12 bits. This is
particularly useful in applications where thermal runaway
conditions must be detected quickly. The thermostat has
a dedicated open-drain output (TOUT). Two thermostat
operating modes, comparator and interrupt, control ther-
mostat operation based on user-defined nonvolatile trip
• Measures Temperature from -55°C to +125°C
• MAX31722 Thermometer Accuracy of ±2°C
• MAX31723 Thermometer Accuracy of ±±.5°C
• Configurable Resolution from 9 Bits to 12 Bits
(±.5°C to ±.±625°C Resolution)
● Reduce Cost with No External Components
● Extend Performance with Low-Voltage, 1.7V to 3.7V
Power-Supply Range
● Dedicated Thermostat Output with Nonvolatile User-
Defined Thresholds for Quick Detection
● Selectable SPI or 3-Wire Interface for Added
Flexibility
®
● Available in 8-Pin μMAX Package for Board Space
Savings
points (T
and T ). Both devices feature a 1.7V to
LOW
HIGH
3.7V supply rail.
Ordering Information
PART
TEMP RANGE
-55NC to +125NC
-55NC to +125NC
-55NC to +125NC
-55NC to +125NC
PIN-PACKAGE
8 FMAX
Applications
MAX31722MUA+
MAX31722MUA+T
MAX31723MUA+
MAX31723MUA+T
Networking Equipment
8 FMAX
Cellular Base Stations
8 FMAX
Industrial Equipment
8 FMAX
Any Thermally Sensitive Systems
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Functional Diagram
PRECISION
OVERSAMPLING
DIGITAL
REFERENCE
MODULATOR
DECIMATOR
V
DD
V
DD
SDI
SDO
CONFIGURATION/
STATUS REGISTER
MAX31722
MAX31723
SCLK
I/O CONTROL
AND
INPUT SENSE
CE
TEMPERATURE
REGISTER
SERMODE
GND
TOUT
T
AND T
REGISTERS
THERMOSTAT
COMPARATOR
HIGH
LOW
µMAX is a registered trademark of Maxim Integrated Products, Inc.
19-5629; Rev 3; 6/21
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Absolute Maximum Ratings
Voltage Range on V
Voltage Range on Any Other Pin Relative to GND...-±.3V to +6.±V
Continuous Power Dissipation (T = +7±NC)
FMAX (derate 4.5mW/NC above +7±NC)......................362mW
EEPROM Programming Temperature Range . ...-4±NC to +85NC
Relative to GND..............-±.3V to +6.±V
Operating Junction Temperature Range ......... -55NC to +125NC
Storage Temperature Range............................ -55NC to +125NC
Lead Temperature (soldering, 1±s) ................................+3±±NC
Soldering Temperature (reflow) ......................................+26±NC
DD
A
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Recommended Operating Characteristics
(T = -55NC to +125NC, unless otherwise noted.)
J
PARAMETER
Supply Voltage
SYMBOL
VDD
CONDITIONS
MIN
1.7
TYP
MAX
3.7
UNITS
(Note 1)
(Note 1)
(Note 1)
V
V
V
Input Logic-High
Input Logic-Low
VIH
±.7 x VDD
-±.3
VDD + ±.3
±.3 x VDD
VIL
DC Electrical Characteristics
(V
DD
= 1.7V to 3.7V, T = -55NC to +125NC, unless otherwise noted.)
J
PARAMETER
SYMBOL
CONDITIONS
-4±NC to +85NC
MIN
TYP
MAX
Q2.±
Q3.±
Q±.5
Q2.±
12
UNITS
MAX31722 Thermometer Error
TERR
NC
-55NC to +125NC
±NC to +7±NC
MAX31723 Thermometer Error
Resolution
TERR
NC
-55NC to +125NC
9
Bits
9-bit conversions
1±-bit conversions
11-bit conversions
12-bit conversions
(Note 2)
25
5±
Conversion Time
tCONVT
ms
1±±
2±±
±.4
Logic ± Output (SDO, TOUT)
Logic 1 Output (SDO)
Leakage Current
VOL
VOH
IL
V
V
VDD -
±.4
(Note 3)
-1
+1
FA
Active temperature conversions (Note 4)
Communication only
115±
1±±
Active Current
ICC
EEPROM writes (-4±NC to +85NC)
115±
FA
FA
EEPROM writes during active temperature
conversions (-4±NC to +85NC)
12±±
2
Shutdown Current
ICC1
Maxim Integrated
│ 2
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
AC Electrical Characteristics: 3-Wire Interface
(V
DD
= 1.7V to 3.7V, T = -55NC to +125NC, unless otherwise noted.) (Figures 1, 2)
J
PARAMETER
SYMBOL
tDC
CONDITIONS
MIN
35
TYP
MAX
UNITS
ns
Data to SCLK Setup
SCLK to Data Hold
SCLK to Data Valid
SCLK Low Time
(Notes 5, 6)
(Notes 5, 6)
(Notes 5, 6, 7)
(Note 6)
tCDH
tCDD
tCL
35
ns
8±
ns
1±±
1±±
DC
ns
SCLK High Time
tCH
(Note 6)
ns
SCLK Frequency
SCLK Rise and Fall
CE to SCLK Setup
SCLK to CE Hold
CE Inactive Time
CE to Output High-Z
SCLK to Output High-Z
tCLK
tR, tF
tCC
(Note 6)
5.±
MHz
ns
2±±
(Note 6)
4±±
1±±
4±±
ns
tCCH
tCWH
tCDZ
tCCZ
(Note 6)
ns
(Note 6)
ns
(Notes 5, 6)
(Notes 5, 6)
4±
4±
ns
ns
AC Electrical Characteristics: SPI Interface
(V
DD
= 1.7V to 3.7V, T = -55NC to +125NC, unless otherwise noted.) (Figures 3, 4)
J
PARAMETER
SYMBOL
tDC
CONDITIONS
MIN
35
TYP
MAX
UNITS
ns
Data to SCLK Setup
SCLK to Data Hold
SCLK to Data Valid
SCLK Low Time
(Notes 5, 6)
(Notes 5, 6)
(Notes 5, 6, 7)
(Note 6)
tCDH
tCDD
tCL
35
ns
8±
ns
1±±
1±±
DC
ns
SCLK High Time
SCLK Frequency
SCLK Rise and Fall
CE to SCLK Setup
SCLK to CE Hold
CE Inactive Time
CE to Output High-Z
tCH
(Note 6)
ns
tCLK
tR, tF
tCC
(Note 6)
5.±
MHz
ns
2±±
(Note 6)
4±±
1±±
4±±
ns
tCCH
tCWH
tCDZ
(Note 6)
ns
(Note 6)
ns
(Notes 5, 6)
4±
ns
AC Electrical Characteristics: EEPROM
(V
DD
= 1.7V to 3.7V, T = -55NC to +125NC, unless otherwise noted.)
J
PARAMETER
SYMBOL
CONDITIONS
-4±NC to +85NC (Note 8)
MIN
TYP
MAX
UNITS
EEPROM Write Cycle Time
tWR
15
ms
-4±NC P TA P +85NC (Note 8)
TA = +25NC (Note 8)
2±,±±±
8±,±±±
EEPROM Write Endurance
NEEWR
Cycles
Note 1: All voltages are referenced to ground. Currents entering the IC are specified positive, and currents exiting the IC are negative.
Note 2: Logic ± voltages are specified at a sink current of 3mA.
Note 3: Logic 1 voltages are specified at a source current of 1mA.
Note 4: I
specified with SCLK = V
and CE = GND.
CC
DD
Note 5: Measured at V = ±.7V x V
or V = ±.3 x V
and 1±ms maximum rise and fall times.
IH
DD
IL
DD
Note 6: Measured with 5±pF load.
Note 7: Measured at V
= ±.7 x V
or V = ±.3 x V . Measured from the 5±% point of SCLK to the V minimum of SDO.
OH
OH
DD
OL
DD
Note 8: V
must be > 2.±V during EEPROM write cycles.
DD
Maxim Integrated
│ 3
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CE
t
CC
SCLK
I/O*
t
CCZ
t
CDZ
t
CDH
t
CDD
t
t
CDD
DC
A0
A1
A7
D0
D1
WRITE ADDRESS BYTE
READ DATA BIT
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 1. Timing Diagram: 3-Wire Read Data Transfer
t
CWH
CE
t
CC
t
CCH
t
R
t
t
F
CL
SCLK
I/O*
t
CDH
t
CH
t
DC
A0
A1
A7
D0
WRITE ADDRESS BYTE
WRITE DATA
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 2. Timing Diagram: 3-Wire Write Data Transfer
Maxim Integrated
│ 4
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CE
t
CC
SCLK
t
CDD
t
t
CDD
CDH
t
DC
SDI
A7
A6
A0
t
CDZ
SDO
D7
D6
D1
D0
WRITE ADDRESS BYTE
READ DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
Figure 3. Timing Diagram: SPI Read Data Transfer
t
CWH
CE
t
CC
t
R
t
CCH
t
F
t
CL
SCLK
SDI
t
CDH
t
CH
t
CDH
t
DC
A7
A6
A0
D7
D0
WRITE ADDRESS BYTE
WRITE DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
Figure 4. Timing Diagram: SPI Write Data Transfer
Maxim Integrated
│ 5
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Typical Operating Characteristics
(T = +25°C, unless otherwise noted.)
A
TEMPERATURE CONVERSION ACTIVE
SUPPLY CURRENT vs. TEMPERATURE
STANDBY SUPPLY CURRENT
vs. TEMPERATURE
1200
1000
800
600
400
200
0
1.4
1.2
V
= 3.7V
DD
V
= 3.7V
DD
1.0
0.8
0.6
0.4
0.2
0
V
= 3.0V
DD
V
= 3.0V
DD
V
= 1.7V
DD
V
= 1.7V
DD
-55 -35 -15
5
25 45 65 85 105 125
-55 -35 -15
5
25 45 65 85 105 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE CONVERSION ERROR
vs. REFERENCE TEMPERATURE
0.5
0.4
12-BIT TEMPERATURE CONVERSIONS
V
DD
= 3.0V
0.3
3σ
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-3
σ
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
Maxim Integrated
│ 6
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Pin Configuration
TOP VIEW
+
TOUT
CE
1
2
3
4
8
7
6
5
V
DD
SERMODE
SDI
MAX31722
MAX31723
SCLK
GND
SDO
µMAX
Pin Description
PIN
NAME
FUNCTION
1
TOUT
Thermostat Output. Open-drain output indicator for internal thermal alarm limits.
Chip Enable. Must be asserted high for communication to take place for either the SPI or 3-wire
interfaces.
2
CE
Serial-Clock Input. Used to synchronize data movement on the serial interface for either SPI or
3-wire interfaces.
3
4
SCLK
GND
Ground. Ground connection.
Serial-Data Output. When SPI communication is selected, the SDO pin is the serial-data output for
the SPI bus. When 3-wire communication is selected, this pin must be connected to the SDI pin.
The SDI and SDO pins function as a single I/O pin when connected together.
5
6
SDO
SDI
Serial-Data Input. When SPI communication is selected, the SDI pin is the serial-data input for the
SPI bus. When 3-wire communication is selected, this pin must be connected to the SDO pin. The
SDI and SDO pins function as a single I/O pin when connected together.
Serial-Interface Mode Input. This pin selects which interface is used. When connected to VDD, SPI
communication is selected. When connected to GND, 3-wire communication is selected.
7
8
SERMODE
VDD
Supply Voltage. Power-supply input.
Detailed Description
temperature conversion results have a default resolution
of 9 bits. In applications where small incremental tem-
perature changes are critical, the user can change the
conversion resolution from 9 bits to 1±, 11, or 12. This is
accomplished by programming the configuration/status
register.
The MAX31722/MAX31723 are factory-calibrated tem-
perature sensors that require no external components.
The user can alter the configuration/status register to
place the device in a continuous temperature conversion
mode or into a one-shot conversion mode. In the continu-
ous conversion mode, the devices continuously convert
the temperature and store the result in the temperature
register. As conversions are performed in the back-
ground, reading the temperature register does not affect
the conversion in progress. In the one-shot temperature
conversion mode, the devices perform one temperature
conversion, store the result in the temperature register,
and then return to the shutdown state. This conversion
mode is ideal for power-sensitive applications. The
The devices can be configured as a thermostat, allow-
ing for the TOUT pin to behave as an interrupt, trigger-
ing when the programmed limits, T
and T
, are
LOW
HIGH
surpassed. The devices can communicate using either a
serial peripheral interface (SPI) or standard 3-wire inter-
face. The user can select either communication standard
through the SERMODE pin, connecting it to V
and to GND for 3-wire.
for SPI
DD
Maxim Integrated
│ 7
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Measuring Temperature
mode is ideal for power-sensitive applications. Details on
how to change the setting after power-up are contained
in the Programming section.
The core of the devices’ functionality is its direct-to-digital
temperature sensor. The devices measure temperature
through the use of an on-chip temperature measure-
ment technique with a -55NC to +125NC operating range.
The devices power up in a power-conserving shutdown
mode. After power-up, the devices can be placed in a
continuous conversion mode or in a one-shot conver-
sion mode. In the continuous conversion mode, the
devices continuously compute the temperature and
store the most recent result in the temperature register at
addresses ±1h (LSB) and ±2h (MSB). As conversions are
performed in the background, reading the temperature
register does not affect the conversion in progress. The
temperature value is not updated until the SPI or 3-wire
interface is inactive. In other words, CE must be inactive
for the temperature register to be updated with the most
recent temperature conversion value. In the one-shot
conversion mode, the devices perform one temperature
conversion and then return to the shutdown mode, storing
temperature in the temperature register. This conversion
The resolution of the temperature conversion is con-
figurable (9, 1±, 11, or 12 bits) with 9 bits reading the
default state. This equates to a temperature resolution
of ±.5NC, ±.25NC, ±.125NC, or ±.±625NC. Following each
conversion, thermal data is stored in the temperature
register in two’s complement format. The information
can be retrieved over the SPI or 3-wire interface with the
address set to the temperature register, ±1h (LSB) and
then ±2h (MSB). Table 1 describes the exact relation-
ship of output data to measured temperature. Table 1
assumes the devices are configured for 12-bit resolution.
If the devices are configured in a lower resolution mode,
those bits contain zeros. The data is transmitted serially
over the digital interface, MSB first for SPI communica-
tion and LSB first for 3-wire communication. The MSB of
the temperature register contains the sign (S) bit, denot-
ing whether the temperature is positive or negative.
6
5
4
3
2
1
±
S
2
2
2
2
2
2
2
±2h
±1h
MSB
(UNITS = NC)
LSB
±
-1
-2
-3
-4
2
2
2
2
±
±
±
Figure 5. Temperature Register Format
Table 1. 12-Bit Resolution Temperature/Data Relationship
TEMPERATURE
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
(NC)
+125
+25.±625
+1±.125
+±.5
±111 11±1 ±±±± ±±±±
±±±1 1±±1 ±±±1 ±±±±
±±±± 1±1± ±±1± ±±±±
±±±± ±±±± 1±±± ±±±±
±±±± ±±±± ±±±± ±±±±
1111 1111 1±±± ±±±±
1111 ±1±1 111± ±±±±
111± ±11± 1111 ±±±±
11±± 1±±1 ±±±± ±±±±
7D±±
191±
±A2±
±±8±
±±±±
FF8±
F5E±
E6F±
C9±±
±
-±.5
-1±.125
-25.±625
-55
Maxim Integrated
│ 8
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Thermostat
The devices’ thermostat can be programmed to power
up in either comparator mode or interrupt mode, which
activate and deactivate the open-drain thermostat output
tion is 9 bits, only the nine MSBs of T
used by the thermostat comparator.
and T
are
HIGH
LOW
If the user does not wish to use the thermostat capa-
bilities of the devices, the TOUT output should be left
unconnected. Note that if the thermostat is not used, the
(TOUT) based on user-programmable trip points (T
HIGH
registers contain
and T
). The T
LOW
and T
HIGH
LOW
T
and T
registers can be used for general stor-
HIGH
LOW
Celsius temperature values and are stored in EEPROM
memory. As such, the values are nonvolatile and can
be programmed prior to installing the devices for stand-
alone operation.
age of system data.
Comparator Mode
When the thermostat is in comparator mode, TOUT can
be programmed to operate with any amount of hysteresis.
The TOUT output becomes active when the measured
The data format of the T
and T
registers are
LOW
HIGH
similar to the temperature registers of ±1h (LSB) and
±2h (MSB) except that the sign bit should always be
set to ± and allows the temperature threshold to be set
from ±°C to 125°C. After every temperature conversion,
the measurement is compared to the values stored in
temperature exceeds the T
value. TOUT then stays
HIGH
active until the first time the temperature falls below the
value stored in T . Putting the devices into shutdown
LOW
mode does not clear TOUT in comparator mode. Figure 6
illustrates thermostat comparator mode operation.
the T
and T
registers. The T
register is
HIGH
LOW
HIGH
assigned to address locations ±3h (LSB) and ±4h (MSB),
and the T register is assigned to address locations
±5h (LSB) and ±6h (MSB). The TOUT output is updated
Interrupt Mode
In interrupt mode, the TOUT output first becomes active
when the measured temperature exceeds the T
value. Once activated, in continuous conversion mode
TOUT can only be cleared by either putting the devices
into shutdown mode or by reading from any register
(configuration/status, temperature, T
on the devices. In one-shot mode, TOUT can only be
LOW
HIGH
based on the result of the comparison and the operating
mode of the devices. The number of T
and T
HIGH
LOW
bits used during the thermostat comparison is equal to
the conversion resolution set by the R1 and R± bits in the
configuration/status register. For example, if the resolu-
, or T
)
HIGH
LOW
cleared by reading from any register (configuration/
T
HIGH
TEMPERATURE
T
LOW
INACTIVE
TOUT OUTPUT—COMPARATOR MODE
ACTIVE
INACTIVE
TOUT OUTPUT—INTERRUPT MODE
ACTIVE
ASSUMES A READ
HAS OCCURED
CONVERSIONS
Figure 6. TOUT Operation Example
Maxim Integrated
│ 9
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Programming
status, temperature, T
either mode, once TOUT has been deactivated, it is only
, or T
) on the devices. In
HIGH
LOW
The area of interest in programming the devices is the
configuration/status register. All programming is done
through the SPI or 3-wire communication interface by
selecting the appropriate address of the desired register
location. Table 2 illustrates the addresses for the device
registers.
reactivated when the measured temperature falls below
the T
value. Thus, this interrupt/clear process is cycli-
LOW
cal between T
and T
events (i.e, T , clear,
HIGH
HIGH
LOW
T
, clear, T
, clear, T
, clear, etc.). Figure 6
LOW
HIGH
LOW
illustrates the thermostat interrupt mode operation.
Configuration/Status Register Programming
Table 2. Register Address Structure
The configuration/status register is accessed in the
devices with the ±±h address for reads and the 8±h
address for writes. Data is read from or written to the
configuration/status register MSB first for SPI communi-
cation and LSB first for 3-wire communication. Table 3
illustrates the format of the register, describes the effect
each bit has on device functionality, and provides the
bit’s factory state.
READ
ADDRESS
(HEX)
WRITE
ADDRESS
(HEX)
ACTIVE REGISTER
±±
±1
±2
±3
±4
±5
±6
8±
Configuration/Status
Temperature LSB
Temperature MSB
THIGH LSB
No access
No access
83
84
85
86
Table 4 defines the resolution of the digital thermometer,
based on the settings of the R1 and R± bits. There is a
direct trade-off between resolution and conversion time,
THIGH MSB
TLOW LSB
TLOW MSB
Table 3. Configuration/Status Register Bit Descriptions
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
±
MEMW
NVB
1SHOT
TM
R1
R±
SD
BIT 7
BIT 6
This bit is always a value of ±.
MEMW: Memory write bit. Power-up state = ±. The user has read/write access to the MEMW bit, which is
stored in the voltage memory.
± = A write of the configuration/status register is stored in RAM memory.
1 = A write of the configuration/status register is stored in EEPROM.
Note: The status of this bit is ignored if a EEPROM write occurs to the other nonvolatile registers, THIGH and
TLOW. The nonvolatile bits of the configuration/status register are written if a EEPROM write cycle occurs to the
THIGH and TLOW registers.
NVB: Nonvolatile memory busy flag. Power-up state = ± and is stored in volatile memory.
± = Indicates that the nonvolatile memory is not busy.
1 = Indicates there is a write to a EEPROM memory cell in progress.
BIT 5
BIT 4
1SHOT: One-shot temperature conversion bit. Power-up state = ± and is stored in volatile memory.
± = Disables 1SHOT mode.
1 = If the SD bit is 1 (continuous temperature conversions are not taking place), a 1 written to the 1SHOT bit
causes the devices to perform one temperature conversion and store the results in the temperature register at
addresses ±1h (LSB) and ±2h (MSB). The bit clears itself to ± upon completion of the temperature conversion.
The user has read/write access to the 1SHOT bit, although writes to this bit are ignored if the SD bit is a ±
(continuous conversion mode).
TM: Thermostat operating mode. Factory power-up state = ±. The user has read/write access to the TM bit,
which is stored in nonvolatile memory.
± = The thermostat output is in comparator mode.
BIT 3
1 = The thermostat output is in interrupt mode.
Maxim Integrated
│ 10
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Table 3. Configuration/Status Register Bit Descriptions (continued)
R1: Thermostat resolution bit 1. Factory power-up state = ± and is stored in nonvolatile memory. Sets the
conversion resolution (see Table 4).
BIT 2
R0: Thermostat resolution bit ±. Factory power-up state = ± and is stored in nonvolatile memory. Sets the
conversion resolution (see Table 4).
BIT 1
SD: Factory power-up state = 1. The user has read/write access to the SD bit, which is stored in nonvolatile
memory.
± = The devices continuously perform temperature conversions and store the last completed result in the
temperature register.
BIT ±
1 = The conversion in progress is completed and stored, and then the devices revert to a low-power shutdown
mode. The communication port remains active.
Serial Peripheral Interface (SPI)
The SPI is a synchronous bus for address and data trans-
fer. The SPI mode of serial communication is selected by
Table 4. Thermometer Resolution
Configuration
connecting SERMODE to V . Four pins are used for the
THERMOMETER
RESOLUTION (BITS)
MAX CONVERSION
DD
R1
R0
SPI: SDO (serial-data out), SDI (serial-data in), CE (chip
enable), and SCLK (serial clock). The devices are the
slave device in an SPI application, with the microcon-
troller being the master. SDI and SDO are the serial-data
input and output pins for the devices, respectively. The
CE input is used to initiate and terminate a data transfer.
SCLK is used to synchronize data movement between
the master (microcontroller) and the slave (IC) devices.
TIME (ms)
±
±
1
1
±
1
±
1
9
25
5±
1±
11
12
1±±
2±±
as depicted in the AC Electrical Characteristics. The user
has read/write access to the R1 and R± bits, which are
nonvolatile. See Table 4.
The serial clock (SCLK), which is generated by the
microcontroller, is active only when CE is high and dur-
ing address and data transfer to any device on the SPI
bus. The inactive clock polarity is programmable in some
microcontrollers. The devices offer an important feature
in that the level of the inactive clock is determined by
sampling SCLK when CE becomes active. Therefore,
either SCLK polarity can be accommodated. Input data
(SDI) is latched on the internal strobe edge and output
data (SDO) is shifted out on the shift edge (see Table 5
and Figure 7). There is one clock for each bit transferred.
Address and data bits are transferred in groups of eight,
MSB first.
Serial Interface
The devices offer the flexibility to choose between two
serial interface modes. They can communicate with the
SPI interface or with a 3-wire interface. The interface
method used is determined by the SERMODE pin. When
SERMODE is connected to V , SPI communication
is selected. When SERMODE is connected to ground,
3-wire communication is selected.
DD
Table 5. Function Table
MODE
CE
SCLK
SDI
SDO
Disable reset
Low
Input disabled
Input disabled
High impedance
CPOL = 1*, SCLK rising
CPOL = ±, SCLK falling
CPOL = 1, SCLK falling
CPOL = ±, SCLK rising
Write
Read
High
High
Data bit latch
X
High impedance
Next data bit shift**
Note: CPHA bit polarity must be set to 1.
*CPOL is the clock polarity bit that is set in the control register of the microcontroller.
**SDO remains at high impedance until 8 bits of data are ready to be shifted out during a read.
Maxim Integrated
│ 11
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CPOL = 1
CE
SHIFT
SHIFT
INTERNAL STROBE
INTERNAL STROBE
SCLK
CPOL = 0
CE
SCLK
NOTE: CPOL IS A BIT THAT IS SET IN THE MICROCONTROLLER’S CONTROL REGISTER.
Figure 7. Serial Clock as a Function of Microcontroller Clock Polarity (CPOL)
Address and Data Bytes
address has been written (see Figure 1±). A single-byte
burst read/write sequentially points through all memory
locations and loops from 7Fh/FFh to ±±h/8±h. Invalid
memory addresses report an FFh value.
Address and data bytes are shifted MSB first into the
serial-data input (SDI) and out of the serial-data output
(SDO). Any transfer requires the address of the byte to
specify a write or a read, followed by one or more bytes of
data. Data is transferred out of the SDO for a read opera-
tion and into the SDI for a write operation. The address
byte is always the first byte entered after CE is driven
high. The MSB (A7) of this byte determines if a read or
write takes place. If A7 is ±, one or more read cycles
occur. If A7 is 1, one or more write cycles occur.
3-Wire Serial-Data Bus
The 3-wire communication mode operates similarly to
the SPI mode. However, in 3-wire mode, there is one
bidirectional I/O instead of separate data-in and data-out
signals. The 3-wire consists of the I/O (SDI and SDO pins
connected together), CE, and SCLK pins. In 3-wire mode,
each byte is shifted in LSB first, unlike SPI mode where
each byte is shifted in MSB first. As is the case with the
SPI mode, an address byte is written to the devices fol-
lowed by a single data byte or multiple data bytes. Figure
11 illustrates a read and write cycle. Figure 12 illustrates
a multiple-byte burst transfer. In 3-wire mode, data is
input on the rising edge of SCLK and output on the falling
edge of SCLK.
Data transfers can occur 1 byte at a time in multiple-byte
burst mode. After CE is driven high, an address is written
to the devices. After the address, one or more data bytes
can be written or read. For a single-byte transfer, 1 byte
is read or written and then CE is driven low (see Figures 8
and 9). For a multiple-byte transfer, however, multiple
bytes can be read or written to the devices after the
Maxim Integrated
│ 12
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CE
SCLK
SDI
A7
A6
A5
A4
A3
A2
A1
A0
SDO
HIGH-Z
D7
D6
D5
D4
D3
D2
D1
D0
Figure 8. SPI Single-Byte Read
CE
SCLK
SDI
A7
A6
A5
A4
A3
A2
A1
A0
D7
D6
D5
D4
D3
D2
D1
D0
SDO
HIGH-Z
Figure 9. SPI Single-Byte Write
CE
SCLK
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
WRITE
SDI
SDI
ADDRESS
BYTE
READ
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
SDO
Figure 10. SPI Multiple-Byte Burst Transfer
Maxim Integrated
│ 13
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CE
SCLK
I/O*
A0
A1
A2
A3
A4
A5
A6
A7
D0
D1
D2
D3
D4
D5
D6
D7
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 11. 3-Wire Single-Byte Transfer
CE
SCLK
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
I/O*
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 12. 3-Wire Multiple-Byte Burst Transfer
Package Information
For the latest package outline information and land patterns, go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-”
in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
8 FMAX
U8+1
21-±±36
9±-±±92
Maxim Integrated
│ 14
www.maximintegrated.com
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
11/1±
3/15
±
1
2
3
Initial release
—
1
Updated Benefits and Features section
Updated Figure 5 and Thermostat section
Updated Figure 5 and Thermostat section
11/2±
6/21
8, 9
8, 9
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2021 Maxim Integrated Products, Inc.
│ 15
相关型号：
MAX31726MTA+
Serial Switch/Digital Sensor, 16 Bit(s), 0.7Cel, Square, 8 Pin, Surface Mount, ROHS-COMPLIANT, TDFN-8
MAXIM
©2020 ICPDF网 联系我们和版权申明