ETC MAX31722 MAX31723

19-5629; Rev 0; 11/10
数字温度计和温度监控器，
带有SPI/3线接口
MAX31722/MAX31723数 字 温 度 计 和 温 度 监 控 器 带 有
SPI™/3线接口，能够提供器件温度的读数。器件无需额
外元件，可真正实现温度到数字的转换。通过SPI接口或3
线串口与器件通信，读取温度值，接口可由用户选择。当
需要更高的温度分辨率时，用户可以调节读数的分辨率，
范围在9位至12位。这一点对于需要快速检测温度失控条
件的系统非常有用。温度监控器具有专用的漏极开路输出
(TOUT)。两种温度监控器工作模式(比较器和中断)能够根
据用户定义的非易失存储门限(THIGH和TLOW)控制温度监
控器的工作。两款器件均工作在1.7V至3.7V电源电压。
应用
网络设备
蜂窝基站
工业设备
特性
S 温度测量无需任何外部元件
S 温度测量范围：-55°C至+125°C
S MAX31722温度测量精度为±2.0°C
S MAX31723温度测量精度为±0.5°C
S 可配置温度计分辨率：9位至12位(0.5°C至0.0625°C分
辨率)
S 温度监控器输出，具有用户定义的非易失门限
S 通过SPI (模式0和模式2)或3线串口读/写数据
S 1.7V至3.7V电源电压范围
S 采用8引脚µMAX®封装
定购信息
热敏感系统
PART
TEMP RANGE
MAX31722MUA+
-55NC to +125NC
PIN-PACKAGE
8 FMAX
MAX31722MUA+T
-55NC to +125NC
8 FMAX
MAX31723MUA+
-55NC to +125NC
8 FMAX
MAX31723MUA+T
-55NC to +125NC
8 FMAX
+表示无铅(Pb)/符合RoHS标准的封装。
T = 卷带包装。
功能框图
VDD
VDD
SDI
SDO
SCLK
CE
SERMODE
GND
PRECISION
REFERENCE
OVERSAMPLING
MODULATOR
DIGITAL
DECIMATOR
CONFIGURATION/
STATUS REGISTER
I/O CONTROL
AND
INPUT SENSE
MAX31722
MAX31723
TEMPERATURE
REGISTER
THIGH AND TLOW
REGISTERS
TOUT
THERMOSTAT
COMPARATOR
SPI是Motorola, Inc.的商标。
µMAX是Maxim Integrated Products, Inc.的注册商标。
_______________________________________________________________________________ Maxim Integrated Products 1
本文是英文数据资料的译文，文中可能存在翻译上的不准确或错误。如需进一步确认，请在您的设计中参考英文资料。
有关价格、供货及订购信息，请联络Maxim亚洲销售中心：10800 852 1249 (北中国区)，10800 152 1249 (南中国区)，
或访问Maxim的中文网站：china.maxim-ic.com。
MAX31722/MAX31723
概述
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
ABSOLUTE MAXIMUM RATINGS
Operating Junction Temperature Range.......... -55NC to +125NC
Storage Temperature Range............................. -55NC to +125NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
Voltage Range on VDD Relative to GND...............-0.3V to +6.0V
Voltage Range on Any Other Pin Relative to GND....-0.3V to +6.0V
Continuous Power Dissipation (TA = +70NC)
FMAX (derate 4.5mW/NC above +70NC).......................362mW
EEPROM Programming Temperature Range.. ...-40NC to +85NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation 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
(TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Supply Voltage
VDD
(Note 1)
Input Logic-High
VIH
(Note 1)
Input Logic-Low
VIL
(Note 1)
MIN
TYP
1.7
0.7 x VDD
-0.3
MAX
UNITS
3.7
V
VDD + 0.3
V
0.3 x VDD
V
DC ELECTRICAL CHARACTERISTICS
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
SYMBOL
MAX31722 Thermometer Error
TERR
MAX31723 Thermometer Error
TERR
CONDITIONS
MIN
-55NC to +125NC
Q3.0
0NC to +70NC
Q0.5
-55NC to +125NC
Q2.0
9
9-bit conversions
Logic 0 Output (SDO, TOUT)
Logic 1 Output (SDO)
Leakage Current
tCONVT
VOL
VOH
50
100
12-bit conversions
200
(Note 2)
(Note 3)
Shutdown Current
2
ICC1
UNITS
NC
NC
Bits
25
11-bit conversions
IL
ICC
12
10-bit conversions
0.4
VDD 0.4
-1
Active temperature conversions (Note 4)
Active Current
MAX
Q2.0
Resolution
Conversion Time
TYP
-40NC to +85NC
ms
V
V
+1
FA
1150
Communication only
100
EEPROM writes (-40NC to +85NC)
1150
EEPROM writes during active temperature
conversions (-40NC to +85NC)
1200
2
FA
FA
数字温度计和温度监控器，
带有SPI/3线接口
MAX31722/MAX31723
AC ELECTRICAL CHARACTERISTICS: 3-WIRE INTERFACE
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
Data to SCLK Setup
tDC
(Notes 5, 6)
35
SCLK to Data Hold
tCDH
(Notes 5, 6)
35
SCLK to Data Valid
tCDD
(Notes 5, 6, 7)
TYP
MAX
UNITS
ns
ns
80
ns
SCLK Low Time
tCL
(Note 6)
100
SCLK High Time
tCH
(Note 6)
100
ns
SCLK Frequency
tCLK
(Note 6)
DC
SCLK Rise and Fall
tR, tF
CE to SCLK Setup
tCC
(Note 6)
400
ns
SCLK to CE Hold
tCCH
(Note 6)
100
ns
CE Inactive Time
tCWH
(Note 6)
400
CE to Output High-Z
tCDZ
(Notes 5, 6)
40
ns
SCLK to Output High-Z
tCCZ
(Notes 5, 6)
40
ns
MAX
UNITS
ns
5.0
200
MHz
ns
ns
AC ELECTRICAL CHARACTERISTICS: SPI INTERFACE
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 3, 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
Data to SCLK Setup
tDC
(Notes 5, 6)
35
SCLK to Data Hold
tCDH
(Notes 5, 6)
35
SCLK to Data Valid
tCDD
(Notes 5, 6, 7)
TYP
ns
ns
80
ns
tCL
(Note 6)
100
SCLK High Time
tCH
(Note 6)
100
SCLK Frequency
tCLK
(Note 6)
DC
SCLK Rise and Fall
tR, tF
CE to SCLK Setup
tCC
(Note 6)
400
ns
SCLK to CE Hold
tCCH
(Note 6)
100
ns
CE Inactive Time
tCWH
(Note 6)
400
CE to Output High-Z
tCDZ
(Notes 5, 6)
SCLK Low Time
ns
ns
5.0
200
MHz
ns
ns
40
ns
MAX
UNITS
15
ms
AC ELECTRICAL CHARACTERISTICS: EEPROM
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
EEPROM Write Cycle Time
EEPROM Write Endurance
SYMBOL
tWR
NEEWR
CONDITIONS
MIN
-40NC to +85NC (Note 8)
-40NC P TA P +85NC (Note 8)
TA = +25NC (Note 8)
20,000
80,000
TYP
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 0 voltages are specified at a sink current of 3mA.
Note 3:Logic 1 voltages are specified at a source current of 1mA.
Note 4:ICC specified with SCLK = VDD and CE = GND.
Note 5:Measured at VIH = 0.7V x VDD or VIL = 0.3 x VDD and 10ms maximum rise and fall times.
Note 6:Measured with 50pF load.
Note 7:Measured at VOH = 0.7 x VDD or VOL = 0.3 x VDD. Measured from the 50% point of SCLK to the VOH minimum of SDO.
Note 8:VDD must be > 2.0V during EEPROM write cycles.
3
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
CE
tCC
SCLK
tCCZ
tCDH
tCDZ
tCDD
tCDD
tDC
A0
I/O*
A1
A7
D0
WRITE ADDRESS BYTE
D1
READ DATA BIT
*I/O IS SDI AND SDO CONNECTED TOGETHER.
图1. 时序图：3线读数据传输
tCWH
CE
tCC
tCCH
tR
tCL
tF
SCLK
tCDH
tCH
tDC
I/O*
A0
A1
WRITE ADDRESS BYTE
*I/O IS SDI AND SDO CONNECTED TOGETHER.
图2. 时序图：3线写数据传输
4
A7
D0
WRITE DATA
数字温度计和温度监控器，
带有SPI/3线接口
MAX31722/MAX31723
CE
tCC
SCLK
tCDD
tCDD
tCDH
tDC
SDI
A7
A6
A0
tCDZ
SDO
D7
D6
WRITE ADDRESS BYTE
D1
D0
READ DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
图3. 时序图：SPI读数据传输
tCWH
CE
tCC
tR
tCL
tCCH
tF
SCLK
tCDH
tCH
tCDH
tDC
SDI
A7
A6
WRITE ADDRESS BYTE
A0
D7
D0
WRITE DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
图4. 时序图：SPI写数据传输
5
典型工作特性
(TA = +25°C, unless otherwise noted.)
TEMPERATURE CONVERSION ACTIVE
SUPPLY CURRENT vs. TEMPERATURE
1.4
VDD = 3.7V
1.2
1.0
ICC (µA)
800
VDD = 3.0V
600
400
VDD = 3.7V
VDD = 1.7V
0.8
VDD = 3.0V
0.6
0.4
200
VDD = 1.7V
0.2
0
0
-55 -35 -15
5
25
45
65
-55 -35 -15
85 105 125
0.5
12-BIT TEMPERATURE CONVERSIONS
VDD = 3.0V
0.4
0.3
3σ
0.2
0.1
0
-0.1
-0.2
-3σ
-0.3
-0.4
-0.5
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
MAX31722/3 toc03
TEMPERATURE CONVERSION ERROR
vs. REFERENCE TEMPERATURE
ERROR (°C)
5
25
45
65
TEMPERATURE (°C)
TEMPERATURE (°C)
6
MAX31722/3 toc02
1000
STANDBY SUPPLY CURRENT
vs. TEMPERATURE
MAX31722/3 toc01
1200
ICC (µA)
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
85 105 125
数字温度计和温度监控器，
带有SPI/3线接口
TOP VIEW
TOUT
1
CE
2
SCLK
3
GND
4
+
MAX31722
MAX31723
8
VDD
7
SERMODE
6
SDI
5
SDO
µMAX
引脚说明
引脚
名称
1
功能
TOUT
2
CE
3
SCLK
4
GND
地，接地连接。
5
SDO
串行数据输出。选择SPI通信时，SDO引脚为SPI总线的串行数据输出；选择3线通信时，必须将该引脚
连接至SDI引脚。SDI和SDO引脚连接在一起时，作为一个I/O引脚。
6
SDI
串行数据输入。选择SPI通信时，SDI引脚为SPI总线的串行数据输入；选择3线通信时，必须将该引脚
连接至SDO引脚。SDI和SDO引脚连接在一起时，作为一个I/O引脚。
7
SERMODE
8
VDD
温度监控器输出。开漏输出，用于指示温度超出内部报警门限。
芯片使能。通过SPI或3线接口进行通信时必须将该引脚置为高电平。
串行时钟输入，用于同步SPI或3线接口的串行数据传输。
串口模式控制输入，通过该引脚选择串口模式。连接至VDD时，选择SPI通信；连接至GND时，选择3线
通信。
供电电源，电源输入。
详细说明
MAX31722/MAX31723为经过工厂校准的温度传感器，无
需任何外部元件。用户可改变配置/状态寄存器，将器件
置于连续温度转换模式或单次转换模式。连续转换模式下，
器件连续转换温度，并将结果存储在温度寄存器中。由于
在后台执行转换，读取温度寄存器不影响正在进行的转换。
单次温度转换模式下，器件执行一次温度转换，将结果存
储在温度寄存器中，然后返回关断状态。该转换模式可理
想用于功耗敏感应用。温度转换结果的默认分辨率为9位，
对于需要检测温度小幅变化的应用，用户可将转换分辨率
从9位更改至10、11或12位，通过设置配置/状态寄存器实
现。
器件可配置为温度监控器，允许TOUT引脚作为中断，温
度超出所设置的门限THIGH和TLOW时，触发中断。器件可
使用串行外设接口(SPI)或标准3线接口通信。用户可通过
SERMODE引脚选择通信标准，连接至VDD时为SPI，连接
至GND时为3线。
7
MAX31722/MAX31723
引脚配置
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
测量温度
用于功耗敏感应用。关于上电后如何更改设置的详细信息，
请参见设置 部分。
器件的核心功能是对温度传感器直接进行数字转换。器件
采用片上温度测量技术测量温度，工作温度范围为-55°C
至+125°C。器件上电时处于节电关断模式；上电后，器
件可置于连续转换模式或单次转换模式。连续转换模式下，
器件连续计算温度，并将最新结果存储在温度寄存器中，
寄存器地址为01h (LSB)和02h (MSB)。由于温度转换在后
台执行，所以读取温度寄存器不影响正在进行的转换。只
有SPI或3线接口停止操作时，才更新温度值。也就是说，
当温度寄存器更新为最新温度转换结果时，CE必须无效。
单次转换模式下，器件执行一次温度转换，然后返回至关
断模式，将温度存储在温度寄存器中，该转换模式可理想
26
S
25
24
MSB
温度转换分辨率可配置(9、10、11或12位)，默认状态为9
位。与之相对应的温度分辨率为0.5°C、0.25°C、0.125°C
或0.0625°C。每次转换之后，温度数据以二进制补码格
式存储在温度寄存器中。将地址设置为温度寄存器01h
(LSB)，然后02h (MSB)，可通过SPI或3线接口读回该信息。
表1所列为输出数据与实测温度的精确关系。表1假设器件
配置为12位分辨率。如果器件配置为低分辨率模式，这些
位包含零。数据通过数字接口串行传输，SPI通信时MSB
在前，3线通信时LSB在前。温度寄存器的MSB包含符号
(S)位，表示正或负温度。
23
22
21
(UNITS = NC)
2-1
2-2
2-3
2-4
0
20
02h
LSB
0
0
0
01h
图5. 温度、THIGH和TLOW寄存器格式
表1. 12位分辨率温度/数据关系
8
TEMPERATURE
(NC)
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
+125
0111 1101 0000 0000
7D00
+25.0625
0001 1001 0001 0000
1910
+10.125
0000 1010 0010 0000
0A20
+0.5
0000 0000 1000 0000
0080
0
0000 0000 0000 0000
0000
-0.5
1111 1111 1000 0000
FF80
-10.125
1111 0101 1110 0000
F5E0
-25.0625
1110 0110 1111 0000
E6F0
-55
1100 1001 0000 0000
C900
数字温度计和温度监控器，
带有SPI/3线接口
比较器模式
器件的温度监控器可设置为上电时处于比较器模式或中
断模式，根据用户可编程门限(THIGH和TLOW)确定是否触
发温度监控器报警/中断指示开漏输出(TOUT)。THIGH和
TLOW寄存器包含二进制补码格式的摄氏度温度值，储存
在EEPROM存储器，采用非易失存储温度数据，独立工作
时，可在安装器件之前进行编程。
温度监控器处于比较器模式时，TOUT可设置工作在任意
滞回状态。实测温度超过THIGH值时，触发TOUT报警输出。
在温度首次下降到TLOW存储门限以下之前，TOUT一直保
持报警状态。比较器模式下，将器件置于关断模式不会清
除TOUT报警，图6所示为温度监控器比较器工作模式。
THIGH和TLOW寄存器的数据格式与温度寄存器(图5)完全相
同。每次温度转换之后，将测量值与存储在THIGH和TLOW
寄存器中的数值进行比较。THIGH寄存器分配的地址为03h
(LSB)和04h (MSB)，TLOW寄存器分配的地址为05h (LSB)
和06h (MSB)。根据比较结果和器件的工作模式，更新
TOUT输出。温度监控器比较时使用的THIGH和TLOW位数
与配置/状态寄存器中R1和R0位设置的转换分辨率相同。
例如，如果分辨率为9位，温度监控器比较器只使用THIGH
和TLOW的9个MSB位。
中断模式下，当测量温度超过THIGH时，触发TOUT中断报
警。一旦触发中断，则在连续转换模式下，只有将器件置
于关断状态，或者读取器件的任一寄存器(配置/状态、温度、
THIGH或TLOW)时，才能清除TOUT中断；单次转换模式下，
只有读取器件的任一寄存器(配置/状态、温度、THIGH或
TLOW)时，才能清除TOUT中断。在这两种模式下，一旦
清除TOUT中断，则只有测量温度下降到TLOW以下时，才
能重新触发中断。因此，这种触发/清除中断的过程是在
THIGH和TLOW事件之间循环进行(即，THIGH、清除中断、
TLOW、清除中断、THIGH、清除中断、TLOW、清除中断、
依次循环)。图6所示为温度监控器的中断工作模式。
如果用户不希望使用器件的温度监控器功能，TOUT输
出应保持浮空。注意，如果未使用温度监控器，THIGH和
TLOW寄存器可用于储存系统数据。
中断模式
THIGH
TEMPERATURE
TLOW
INACTIVE
TOUT OUTPUT—COMPARATOR MODE
ACTIVE
INACTIVE
TOUT OUTPUT—INTERRUPT MODE
ACTIVE
ASSUMES A READ
HAS OCCURED
CONVERSIONS
图6. TOUT工作示例
9
MAX31722/MAX31723
温度监控器
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
设置
表2. 寄存器地址结构
READ
ADDRESS
(HEX)
WRITE
ADDRESS
(HEX)
ACTIVE REGISTER
00
80
Configuration/Status
01
No access
Temperature LSB
02
No access
Temperature MSB
03
83
THIGH LSB
04
84
THIGH MSB
05
85
TLOW LSB
06
86
TLOW MSB
表3. 配置/状态寄存器位说明
10
设置器件时所关心的区域是配置/状态寄存器。利用SPI或
3线通信接口，通过选择相应寄存器位置的对应地址，即
可完成所有设置。表2所示为器件寄存器的地址。
配置/状态寄存器设置
在器件中存取配置/状态寄存器时，读操作使用地址00h，
写操作使用地址80h。读或写配置/状态寄存器的数据时，
SPI通信为MSB在前，3线通信为LSB在前。表3所示为寄
存器的格式，说明了每位的功能，并提供每位的出厂状态。
表4根据R1和R0位的设置，定义数字温度计的分辨率。如
交流电气特性 部分所述，分辨率和转换时间之间存在一定
的折中关系。用户可对R1和R0位进行读写操作，这两位
为非易失位，参见表4。
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0
MEMW
NVB
1SHOT
TM
R1
R0
SD
BIT 7
This bit is always a value of 0.
BIT 6
MEMW: Memory write bit. Power-up state = 0. The user has read/write access to the MEMW bit, which is
stored in the voltage memory.
0 = 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.
BIT 5
NVB: Nonvolatile memory busy flag. Power-up state = 0 and is stored in volatile memory.
0 = Indicates that the nonvolatile memory is not busy.
1 = Indicates there is a write to a EEPROM memory cell in progress.
BIT 4
1SHOT: One-shot temperature conversion bit. Power-up state = 0 and is stored in volatile memory.
0 = 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 01h (LSB) and 02h (MSB). The bit clears itself to 0 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 0
(continuous conversion mode).
BIT 3
TM: Thermostat operating mode. Factory power-up state = 0. The user has read/write access to the TM bit,
which is stored in nonvolatile memory.
0 = The thermostat output is in comparator mode.
1 = The thermostat output is in interrupt mode.
数字温度计和温度监控器，
带有SPI/3线接口
BIT 2
R1: Thermostat resolution bit 1. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the
conversion resolution (see Table 4).
BIT 1
R0: Thermostat resolution bit 0. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the
conversion resolution (see Table 4).
BIT 0
SD: Factory power-up state = 1. The user has read/write access to the SD bit, which is stored in nonvolatile
memory.
0 = The devices continuously perform temperature conversions and store the last completed result in the
temperature register.
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.
串行外设接口(SPI)
表4. 温度计分辨率配置
THERMOMETER
RESOLUTION (BITS)
MAX CONVERSION
TIME (ms)
0
9
25
1
10
50
1
0
11
100
1
1
12
200
R1
R0
0
0
串行接口
器件能够灵活地在两种串行接口模式之间进行选择。器件
可采用SPI接口或3线接口进行通信。使用的接口方法由
SERMODE引脚决定。SERMODE连接至VDD时，选择SPI
通信；SERMODE连接至地时，选择3线通信。
SPI是一种用于地址和数据传输的同步总线。将SERMODE
连接至VDD，选择SPI模式串行通信。SPI使用四个引脚：
SDO (串行数据输出)、SDI (串行数据输入)、CE (芯片使能)
和SCLK (串行时钟)。SPI应用中，器件为从器件，微控制
器为主控制器。SDI和SDO分别是器件的串行数据输入和
输出引脚。CE输入用于启动和终止数据传输。SCLK用于
同步主控制器(微控制器)和从器件(IC)之间的数据传输。
串行时钟(SCLK)由微控制器产生，只有CE为高电平时且将
地址和数据传输至SPI总线上任一器件期间，该时钟才有
效。在有些微控制器中需设置时钟无效时的极性。器件具
有一项重要功能：CE变为有效时，通过采样SCLK，确定
时钟无效时的电平。因此，可以支持任一SCLK极性。在
内部选通沿上锁存输入数据(SDI)，在翻转沿上移出输出数
据(SDO) (参见表5和图7)。传输的每一位均有一个时钟脉
冲。地址和数据位按八位一组传输，MSB在前。
表5. 功能表
MODE
CE
SCLK
SDI
SDO
Disable reset
Low
Input disabled
Input disabled
High impedance
Write
High
Data bit latch
High impedance
Read
High
X
Next data bit shift**
CPOL = 1*, SCLK rising
CPOL = 0, SCLK falling
CPOL = 1, SCLK falling
CPOL = 0, SCLK rising
注：CPHA位极性必须设置为1。
*CPOL为时钟极性位，在微控制器的控制寄存器中进行设置。
**读操作期间，在8位数据准备好之前，SDO保持高阻态。
11
MAX31722/MAX31723
表3. 配置/状态寄存器位说明(续)
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
CPOL = 1
CE
SHIFT
INTERNAL STROBE
SHIFT
INTERNAL STROBE
SCLK
CPOL = 0
CE
SCLK
NOTE: CPOL IS A BIT THAT IS SET IN THE MICROCONTROLLER’S CONTROL REGISTER.
图7. 串行时钟作为微控制器时钟极性(CPOL)的功能
地址和数据字节
地址和数据字节移入串行数据输入(SDI)和移出串行数据
输出(SDO)时，MSB在前。任何传输都需要在地址字节指
定写入或读取操作，后面跟一个或多个数据字节。读操作
时，从SDO输出数据；写操作时，数据输入至SDI。CE驱
动为高电平后，输入的第一个字节总为地址字节。该字节
的MSB (A7)决定是读操作还是写操作。如果A7为0，发生
一次或多次读循环；如果A7为1，发生一次或多次写循环。
在多字节突发模式下，数据传输可每次1个字节。CE驱动
为高电平后，将地址写入器件。地址的后面可写或读一个
或多个数据字节。对于单字节传输，读或写1个字节，然
后CE驱动为低电平(见图8和图9)。然而，对于多字节传输，
写入地址后，可以对器件读或写多个字节(见图10)。单字
12
节突发读/写操作按次序指向所有存储器位置，并从7Fh/
FFh循环至00h/80h。存储器地址无效时，报告FFh值。
3线串行数据总线
3线通信模式与SPI模式的工作方式类似。但是，3线模式
下，采用一个双向I/O，而非独立的数据输入和数据输出
信号。3线由I/O (SDI和SDO引脚连接在一起)、CE和SCLK
引脚组成。3线模式下，每个字节首先移入LSB，而SPI模
式下每个字节首先移入MSB。与SPI模式相同，对器件写
入地址字节，其后跟一个数据字节或多个数据字节。图11
所示为读、写时序；图12所示为多字节突发传输模式。3
线模式下，在SCLK的上升沿输入数据，在SCLK的下降沿
输出数据。
数字温度计和温度监控器，
带有SPI/3线接口
MAX31722/MAX31723
CE
SCLK
SDI
A7
SDO
A6
A5
A4
A3
A2
A1
A0
HIGH-Z
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
图8. SPI单字节读操作
CE
SCLK
SDI
A7
SDO
A6
A5
A4
A3
A2
A1
A0
HIGH-Z
图9. SPI单字节写操作
CE
SCLK
WRITE
SDI
ADDRESS
BYTE
SDI
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
READ
SDO
图10. SPI多字节突发传输模式
13
MAX31722/MAX31723
数字温度计和温度监控器，
带有SPI/3线接口
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.
图11. 3线单字节传输
CE
SCLK
I/O*
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
*I/O IS SDI AND SDO CONNECTED TOGETHER.
图12. 3线多字节突发传输模式
封装信息
如需最近的封装外形信息和焊盘布局(占位面积)，请查询china.maxim-ic.com/packages。请注意，封装编码中的“+”
、“#”或“-”
仅表示RoHS状态。封装图中可能包含不同的尾缀字符，但封装图只与封装有关，与RoHS状态无关。
14
封装类型
封装编码
8 FMAX
U8+1
外形编号
21-0036
焊盘布局编号
90-0092
数字温度计和温度监控器，
带有SPI/3线接口
修订号
修订日期
0
11/10
说明
修改页
—
最初版本。
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Maxim Integrated Products, Inc. 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2010 Maxim Integrated Products 15
Maxim是Maxim Integrated Products，Inc.的注册商标。
MAX31722/MAX31723
修订历史
MAX31722, MAX31723 数字温度计和温度监控器，带有SPI/3线接口 - 概述
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MAX31722, MAX31723
数字温度计和温度监控器，带有SPI/3线接口
业内首款低电压3线/SPI温度传感器，简化低功耗系统设计
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MAX31722/MAX31723数字温度计和温度监控器带有SPI™/3线接口，能够提供器件温度的读数。器件无需额外元
件，可真正实现温度到数字的转换。通过SPI接口或3线串口与器件通信，读取温度值，接口可由用户选择。当需
要更高的温度分辨率时，用户可以调节读数的分辨率，范围在9位至12位。这一点对于需要快速检测温度失控条件
的系统非常有用。温度监控器具有专用的漏极开路输出(/TOUT)。两种温度监控器工作模式(比较器和中断)能够根
据用户定义的非易失存储门限(T HIGH 和TLOW )控制温度监控器的工作。两款器件均工作在1.7V至3.7V电源电压。
Rev. 0 (PDF, 768kB)
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现备有评估板：MAX31723PMB1 MAXPMBAE
关键特性
温度测量无需任何外部元件
温度测量范围：-55°C至+125°C
MAX31722温度测量精度为±2.0°C
MAX31723温度测量精度为±0.5°C
可配置温度计分辨率：9位至12位(0.5°C至0.0625°C分辨率)
温度监控器输出，具有用户定义的非易失门限
通过SPI (模式0和模式2)或3线串口读/写数据
1.7V至3.7V电源电压范围
采用8引脚µMAX®封装
关键特性:
Temperature Sensors
Part
Number
Sensor
Type
Alarm
Output
Functions
http://china.maxim-ic.com/datasheet/index.mvp/id/6975[2012-08-28 8:49:35]
Interface
Accuracy
(±°C)
Parasite
Pwr.
Temp.
Thresh.
Temp.
Resolution
(bits)
Oper. Temp.
(°C)
Smallest
Available
Pckg.
(mm 2 )
Budgetary Price
MAX31722, MAX31723 数字温度计和温度监控器，带有SPI/3线接口 - 概述
max
w/pins
MAX31722 MAX31723 Local
Overt
Memory
Single
Temperature
Alarm
Standalone
Thermostat
2
3Wire/SPI
3-Wire
$0.79 @1k
No
0.5
Programmable
(NV)
12
-55 to +125
查看所有Temperature Sensors (104)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may
differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized
distributor.
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http://china.maxim-ic.com/datasheet/index.mvp/id/6975[2012-08-28 8:49:35]
See Notes
15.6
$1.44 @1k
MAX31722, MAX31723 数字温度计和温度监控器，带有SPI/3线接口 - 概述
关键指标
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参考文献： 19- 5629 Rev. 0; 2010- 11- 16
本页最后一次更新: 2010- 11- 16
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© 2012 Maxim Integrated Products版权所有
http://china.maxim-ic.com/datasheet/index.mvp/id/6975[2012-08-28 8:49:35]
19-5629; Rev 0; 11/10
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
The MAX31722/MAX31723 digital thermometers and
thermostats with an SPI™/3-wire interface provide temperature 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 thermostat operation based on user-defined nonvolatile trip
points (THIGH and TLOW). Both devices feature a 1.7V to
3.7V supply rail.
Features
S Temperature Measurements Require No External
Components
S Measures Temperatures from -55NC to +125NC
S MAX31722 Thermometer Accuracy is ±2.0NC
S MAX31723 Thermometer Accuracy is ±0.5NC
S Thermometer Resolution is Configurable from 9
to 12 Bits (0.5NC to 0.0625NC Resolution)
S Thermostat Output with User-Defined Nonvolatile
Thresholds
S Data is Read from/Written to by SPI (Mode 0 and 2)
or 3-Wire Serial Interface
S 1.7V to 3.7V Power-Supply Range
S Available in 8-Pin µMAX® Package
Ordering Information
Applications
PART
TEMP RANGE
Networking Equipment
MAX31722MUA+
-55NC to +125NC
8 FMAX
Cellular Base Stations
MAX31722MUA+T
-55NC to +125NC
8 FMAX
MAX31723MUA+
-55NC to +125NC
8 FMAX
MAX31723MUA+T
-55NC to +125NC
8 FMAX
Industrial Equipment
Any Thermally Sensitive Systems
PIN-PACKAGE
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
Functional Diagram
VDD
VDD
SDI
SDO
SCLK
CE
SERMODE
GND
PRECISION
REFERENCE
OVERSAMPLING
MODULATOR
DIGITAL
DECIMATOR
CONFIGURATION/
STATUS REGISTER
I/O CONTROL
AND
INPUT SENSE
MAX31722
MAX31723
TEMPERATURE
REGISTER
THIGH AND TLOW
REGISTERS
TOUT
THERMOSTAT
COMPARATOR
SPI is a trademark of Motorola, Inc.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX31722/MAX31723
General Description
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
ABSOLUTE MAXIMUM RATINGS
Voltage Range on VDD Relative to GND...............-0.3V to +6.0V
Voltage Range on Any Other Pin Relative to GND....-0.3V to +6.0V
Continuous Power Dissipation (TA = +70NC)
FMAX (derate 4.5mW/NC above +70NC).......................362mW
EEPROM Programming Temperature Range.. ...-40NC to +85NC
Operating Junction Temperature Range.......... -55NC to +125NC
Storage Temperature Range............................. -55NC to +125NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation 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
(TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Supply Voltage
VDD
(Note 1)
Input Logic-High
VIH
(Note 1)
Input Logic-Low
VIL
(Note 1)
MIN
TYP
1.7
0.7 x VDD
-0.3
MAX
UNITS
3.7
V
VDD + 0.3
V
0.3 x VDD
V
DC ELECTRICAL CHARACTERISTICS
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
SYMBOL
MAX31722 Thermometer Error
TERR
MAX31723 Thermometer Error
TERR
CONDITIONS
MIN
-55NC to +125NC
Q3.0
0NC to +70NC
Q0.5
-55NC to +125NC
Q2.0
9
9-bit conversions
tCONVT
MAX
Q2.0
Resolution
Conversion Time
TYP
-40NC to +85NC
12
10-bit conversions
50
11-bit conversions
100
12-bit conversions
200
Logic 0 Output (SDO, TOUT)
(Note 2)
0.4
Logic 1 Output (SDO)
VOH
(Note 3)
IL
Active Current
Shutdown Current
2
ICC
ICC1
VDD 0.4
-1
Active temperature conversions (Note 4)
NC
NC
Bits
25
VOL
Leakage Current
UNITS
ms
V
V
+1
FA
1150
Communication only
100
EEPROM writes (-40NC to +85NC)
1150
EEPROM writes during active temperature
conversions (-40NC to +85NC)
1200
2
FA
FA
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
MAX31722/MAX31723
AC ELECTRICAL CHARACTERISTICS: 3-WIRE INTERFACE
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
Data to SCLK Setup
tDC
(Notes 5, 6)
35
SCLK to Data Hold
tCDH
(Notes 5, 6)
35
SCLK to Data Valid
tCDD
(Notes 5, 6, 7)
SCLK Low Time
TYP
MAX
UNITS
ns
ns
80
ns
tCL
(Note 6)
100
ns
SCLK High Time
tCH
(Note 6)
100
SCLK Frequency
tCLK
(Note 6)
DC
SCLK Rise and Fall
tR, tF
CE to SCLK Setup
tCC
(Note 6)
400
ns
SCLK to CE Hold
tCCH
(Note 6)
100
ns
CE Inactive Time
tCWH
(Note 6)
400
CE to Output High-Z
tCDZ
(Notes 5, 6)
40
ns
SCLK to Output High-Z
tCCZ
(Notes 5, 6)
40
ns
MAX
UNITS
ns
5.0
MHz
200
ns
ns
AC ELECTRICAL CHARACTERISTICS: SPI INTERFACE
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 3, 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
Data to SCLK Setup
tDC
(Notes 5, 6)
35
SCLK to Data Hold
tCDH
(Notes 5, 6)
35
SCLK to Data Valid
tCDD
(Notes 5, 6, 7)
SCLK Low Time
TYP
ns
ns
80
ns
tCL
(Note 6)
100
ns
SCLK High Time
tCH
(Note 6)
100
SCLK Frequency
tCLK
(Note 6)
DC
SCLK Rise and Fall
tR, tF
CE to SCLK Setup
tCC
(Note 6)
400
ns
SCLK to CE Hold
tCCH
(Note 6)
100
ns
CE Inactive Time
tCWH
(Note 6)
400
CE to Output High-Z
tCDZ
(Notes 5, 6)
ns
5.0
MHz
200
ns
ns
40
ns
MAX
UNITS
15
ms
AC ELECTRICAL CHARACTERISTICS: EEPROM
(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)
PARAMETER
EEPROM Write Cycle Time
EEPROM Write Endurance
SYMBOL
tWR
NEEWR
CONDITIONS
MIN
-40NC to +85NC (Note 8)
-40NC P TA P +85NC (Note 8)
20,000
TA = +25NC (Note 8)
80,000
TYP
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 0 voltages are specified at a sink current of 3mA.
Note 3: Logic 1 voltages are specified at a source current of 1mA.
Note 4: ICC specified with SCLK = VDD and CE = GND.
Note 5: Measured at VIH = 0.7V x VDD or VIL = 0.3 x VDD and 10ms maximum rise and fall times.
Note 6: Measured with 50pF load.
Note 7: Measured at VOH = 0.7 x VDD or VOL = 0.3 x VDD. Measured from the 50% point of SCLK to the VOH minimum of SDO.
Note 8: VDD must be > 2.0V during EEPROM write cycles.
3
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CE
tCC
SCLK
tCCZ
tCDH
tCDZ
tCDD
tCDD
tDC
A0
I/O*
A1
A7
D0
WRITE ADDRESS BYTE
D1
READ DATA BIT
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 1. Timing Diagram: 3-Wire Read Data Transfer
tCWH
CE
tCC
tCCH
tR
tCL
tF
SCLK
tCDH
tCH
tDC
I/O*
A0
A1
WRITE ADDRESS BYTE
*I/O IS SDI AND SDO CONNECTED TOGETHER.
Figure 2. Timing Diagram: 3-Wire Write Data Transfer
4
A7
D0
WRITE DATA
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
MAX31722/MAX31723
CE
tCC
SCLK
tCDD
tCDD
tCDH
tDC
SDI
A7
A6
A0
tCDZ
SDO
D7
D6
WRITE ADDRESS BYTE
D1
D0
READ DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
Figure 3. Timing Diagram: SPI Read Data Transfer
tCWH
CE
tCC
tR
tCL
tCCH
tF
SCLK
tCDH
tCH
tCDH
tDC
SDI
A7
A6
WRITE ADDRESS BYTE
A0
D7
D0
WRITE DATA BYTE
NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.
Figure 4. Timing Diagram: SPI Write Data Transfer
5
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
TEMPERATURE CONVERSION ACTIVE
SUPPLY CURRENT vs. TEMPERATURE
1.4
VDD = 3.7V
1.2
1.0
ICC (µA)
800
VDD = 3.0V
600
400
VDD = 3.7V
VDD = 1.7V
0.8
VDD = 3.0V
0.6
0.4
200
VDD = 1.7V
0.2
0
0
-55 -35 -15
5
25
45
65
-55 -35 -15
85 105 125
0.5
12-BIT TEMPERATURE CONVERSIONS
VDD = 3.0V
0.4
0.3
3σ
0.2
0.1
0
-0.1
-0.2
-3σ
-0.3
-0.4
-0.5
-40
-20
0
20
40
TEMPERATURE (°C)
60
80
MAX31722/3 toc03
TEMPERATURE CONVERSION ERROR
vs. REFERENCE TEMPERATURE
ERROR (°C)
5
25
45
65
TEMPERATURE (°C)
TEMPERATURE (°C)
6
MAX31722/3 toc02
1000
STANDBY SUPPLY CURRENT
vs. TEMPERATURE
MAX31722/3 toc01
1200
ICC (µA)
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
85 105 125
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
MAX31722/MAX31723
Pin Configuration
TOP VIEW
TOUT
1
CE
2
SCLK
3
GND
4
+
MAX31722
MAX31723
8
VDD
7
SERMODE
6
SDI
5
SDO
µMAX
Pin Description
PIN
NAME
1
TOUT
FUNCTION
2
CE
3
SCLK
Serial-Clock Input. Used to synchronize data movement on the serial interface for either SPI or
3-wire interfaces.
4
GND
Ground. Ground connection.
5
SDO
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.
6
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.
7
SERMODE
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.
8
VDD
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.
Supply Voltage. Power-supply input.
Detailed Description
The MAX31722/MAX31723 are factory-calibrated temperature 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 continuous conversion mode, the devices continuously convert
the temperature and store the result in the temperature
register. As conversions are performed in the background, 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
temperature conversion results have a default resolution
of 9 bits. In applications where small incremental temperature changes are critical, the user can change the
conversion resolution from 9 bits to 10, 11, or 12. This is
accomplished by programming the configuration/status
register.
The devices can be configured as a thermostat, allowing for the TOUT pin to behave as an interrupt, triggering when the programmed limits, THIGH and TLOW, are
surpassed. The devices can communicate using either a
serial peripheral interface (SPI) or standard 3-wire interface. The user can select either communication standard
through the SERMODE pin, connecting it to VDD for SPI
and to GND for 3-wire.
7
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 measurement 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 conversion mode. In the continuous conversion mode, the
devices continuously compute the temperature and
store the most recent result in the temperature register at
addresses 01h (LSB) and 02h (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
26
S
25
24
The resolution of the temperature conversion is configurable (9, 10, 11, or 12 bits) with 9 bits reading the
default state. This equates to a temperature resolution
of 0.5NC, 0.25NC, 0.125NC, or 0.0625NC. 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, 01h (LSB) and
then 02h (MSB). Table 1 describes the exact relationship 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 communication and LSB first for 3-wire communication. The MSB of
the temperature register contains the sign (S) bit, denoting whether the temperature is positive or negative.
23
MSB
22
21
2-2
2-3
2-4
0
02h
LSB
(UNITS = NC)
2-1
20
0
0
0
01h
Figure 5. Temperature, THIGH, and TLOW Register Format
Table 1. 12-Bit Resolution Temperature/Data Relationship
8
TEMPERATURE
(NC)
DIGITAL OUTPUT
(BINARY)
DIGITAL OUTPUT
(HEX)
7D00
+125
0111 1101 0000 0000
+25.0625
0001 1001 0001 0000
1910
+10.125
0000 1010 0010 0000
0A20
+0.5
0000 0000 1000 0000
0080
0000
0
0000 0000 0000 0000
-0.5
1111 1111 1000 0000
FF80
-10.125
1111 0101 1110 0000
F5E0
-25.0625
1110 0110 1111 0000
E6F0
-55
1100 1001 0000 0000
C900
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
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
(TOUT) based on user-programmable trip points (THIGH
and TLOW). The THIGH and TLOW registers contain
Celsius temperature values in two’s complement format
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.
The data format of the THIGH and TLOW registers is
identical to that of the temperature register (Figure 5).
After every temperature conversion, the measurement is
compared to the values stored in the THIGH and TLOW
registers. The THIGH register is assigned to address
locations 03h (LSB) and 04h (MSB), and the TLOW register is assigned to address locations 05h (LSB) and
06h (MSB). The TOUT output is updated based on the
result of the comparison and the operating mode of the
devices. The number of THIGH and TLOW bits used during the thermostat comparison is equal to the conversion
resolution set by the R1 and R0 bits in the configuration/
status register. For example, if the resolution is 9 bits,
only the nine MSBs of THIGH and TLOW are used by the
thermostat comparator.
If the user does not wish to use the thermostat capabilities of the devices, the TOUT output should be left
unconnected. Note that if the thermostat is not used, the
THIGH and TLOW registers can be used for general storage 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 temperature exceeds the THIGH value. TOUT
then stays active until the first time the temperature falls
below the value stored in TLOW. Putting the devices into
shutdown mode does not clear TOUT in comparator
mode. Figure 6 illustrates thermostat comparator mode
operation.
Interrupt Mode
In interrupt mode, the TOUT output first becomes active
when the measured temperature exceeds the THIGH
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, THIGH, or TLOW)
on the devices. In one-shot mode, TOUT can only be
cleared by reading from any register (configuration/
status, temperature, THIGH, or TLOW) on the devices.
THIGH
TEMPERATURE
TLOW
INACTIVE
TOUT OUTPUT—COMPARATOR MODE
ACTIVE
INACTIVE
TOUT OUTPUT—INTERRUPT MODE
ACTIVE
ASSUMES A READ
HAS OCCURED
CONVERSIONS
Figure 6. TOUT Operation Example
9
MAX31722/MAX31723
Thermostat
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
In either mode, once TOUT has been deactivated, it is
only reactivated when the measured temperature falls
below the TLOW value. Thus, this interrupt/clear process is cyclical between THIGH and TLOW events (i.e,
THIGH, clear, TLOW, clear, THIGH, clear, TLOW, clear,
etc.). Figure 6 illustrates the thermostat interrupt mode
operation.
Table 2. Register Address Structure
READ
ADDRESS
(HEX)
Programming
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.
Configuration/Status Register Programming
WRITE
ADDRESS
(HEX)
ACTIVE REGISTER
00
80
Configuration/Status
01
No access
Temperature LSB
02
No access
Temperature MSB
03
83
THIGH LSB
04
84
THIGH MSB
05
85
TLOW LSB
06
86
TLOW MSB
The configuration/status register is accessed in the
devices with the 00h address for reads and the 80h
address for writes. Data is read from or written to the
configuration/status register MSB first for SPI communication 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.
Table 4 defines the resolution of the digital thermometer,
based on the settings of the R1 and R0 bits. There is a
direct trade-off between resolution and conversion time,
Table 3. Configuration/Status Register Bit Descriptions
10
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0
MEMW
NVB
1SHOT
TM
R1
R0
SD
BIT 7
This bit is always a value of 0.
BIT 6
MEMW: Memory write bit. Power-up state = 0. The user has read/write access to the MEMW bit, which is
stored in the voltage memory.
0 = 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.
BIT 5
NVB: Nonvolatile memory busy flag. Power-up state = 0 and is stored in volatile memory.
0 = Indicates that the nonvolatile memory is not busy.
1 = Indicates there is a write to a EEPROM memory cell in progress.
BIT 4
1SHOT: One-shot temperature conversion bit. Power-up state = 0 and is stored in volatile memory.
0 = 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 01h (LSB) and 02h (MSB). The bit clears itself to 0 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 0
(continuous conversion mode).
BIT 3
TM: Thermostat operating mode. Factory power-up state = 0. The user has read/write access to the TM bit,
which is stored in nonvolatile memory.
0 = The thermostat output is in comparator mode.
1 = The thermostat output is in interrupt mode.
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
BIT 2
R1: Thermostat resolution bit 1. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the conversion resolution (see Table 4).
BIT 1
R0: Thermostat resolution bit 0. Factory power-up state = 0 and is stored in nonvolatile memory. Sets the conversion resolution (see Table 4).
BIT 0
SD: Factory power-up state = 1. The user has read/write access to the SD bit, which is stored in nonvolatile
memory.
0 = The devices continuously perform temperature conversions and store the last completed result in the temperature register.
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)
Table 4. Thermometer Resolution
Configuration
THERMOMETER
RESOLUTION (BITS)
MAX CONVERSION
TIME (ms)
0
9
25
1
10
50
1
0
11
100
1
1
12
200
R1
R0
0
0
as depicted in the AC Electrical Characteristics. The user
has read/write access to the R1 and R0 bits, which are
nonvolatile. See Table 4.
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 VDD, SPI communication
is selected. When SERMODE is connected to ground,
3-wire communication is selected.
Table 5. Function Table
MODE
CE
Disable reset
Low
Write
High
Read
High
The SPI is a synchronous bus for address and data
transfer. The SPI mode of serial communication is selected by connecting SERMODE to VDD. Four pins are used
for the 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 microcontroller 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.
The serial clock (SCLK), which is generated by the
microcontroller, is active only when CE is high and during 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.
SCLK
SDI
SDO
Input disabled
Input disabled
High impedance
Data bit latch
High impedance
X
Next data bit shift**
CPOL = 1*, SCLK rising
CPOL = 0, SCLK falling
CPOL = 1, SCLK falling
CPOL = 0, SCLK rising
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.
11
MAX31722/MAX31723
Table 3. Configuration/Status Register Bit Descriptions (continued)
MAX31722/MAX31723
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
CPOL = 1
CE
SHIFT
INTERNAL STROBE
SHIFT
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 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 operation 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 0, one or more read cycles
occur. If A7 is 1, one or more write cycles occur.
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 address has been written (see Figure 10). A
12
single-byte burst read/write sequentially points through
all memory locations and loops from 7Fh/FFh to 00h/80h.
Invalid memory addresses report an FFh value.
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 dataout 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 followed 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.
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
MAX31722/MAX31723
CE
SCLK
SDI
A7
SDO
A6
A5
A4
A3
A2
A1
A0
HIGH-Z
D7
D6
D5
D4
D3
D2
D1
D0
D7
D6
D5
D4
D3
D2
D1
D0
Figure 8. SPI Single-Byte Read
CE
SCLK
SDI
A7
SDO
A6
A5
A4
A3
A2
A1
A0
HIGH-Z
Figure 9. SPI Single-Byte Write
CE
SCLK
WRITE
SDI
ADDRESS
BYTE
SDI
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
READ
SDO
Figure 10. SPI Multiple-Byte Burst Transfer
13
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
I/O*
ADDRESS
BYTE
DATA
BYTE 0
DATA
BYTE 1
DATA
BYTE N
*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.maxim-ic.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.
14
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
8 FMAX
U8+1
21-0036
90-0092
Digital Thermometers and Thermostats
with SPI/3-Wire Interface
REVISION
NUMBER
REVISION
DATE
0
11/10
DESCRIPTION
Initial release
PAGES
CHANGED
—
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2010
Maxim Integrated Products 15
Maxim is a registered trademark of Maxim Integrated Products, Inc.
MAX31722/MAX31723
Revision History