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MAX31725/MAX31726

±0.5°C Local Temperature Sensors

General Description

The MAX31725/MAX31726 temperature sensors

accurately measure temperature and provide an

overtemperature alarm/interrupt/shutdown output. These

devices convert the temperature measurements to digital

form using a high-resolution, sigma-delta, analog-to-

digital converter (ADC). Accuracy is Q0.5NC from -40NC

to +105NC. Communication is through an I

C-compatible

2-wire serial interface.

The I

C serial interface accepts standard write byte, read

byte, send byte, and receive byte commands to read

the temperature data and configure the behavior of the

open-drain overtemperature shutdown output.

The MAX31725 features three address select lines with a

total of 32 available addresses. The MAX31726 features

two address select lines with a total of 16 available

addresses and a RESET input. The sensors have a

2.5V to 3.7V supply voltage range, low 600FA supply

current, and a lockup-protected I

C-compatible interface

that make them ideal for a wide range of applications,

including PCs, electronic test equipment, and office

electronics.

Both devices are available in an 8-pin TDFN package and

operate over the -55NC to +150NC temperature range.

Benefits and Features

S High Accuracy and Low-Voltage Operation Aids

Designers in Meeting Error and Power Budgets

±0.5°C Accuracy from -40°C to +105°C

16-Bit (0.00390625°C) Temperature Resolution

2.5V to 3.7V Supply Voltage Range

S One-Shot and Shutdown Modes Help Reduce

Power Usage

925μA (max) Operating Supply Current

S Extended Temperature Range Enables

Measurements in High Temperature Systems

(Measures Up to +150°C)

S Digital Functions Make Integration Easier into Any

System

Selectable Timeout Prevents Bus Lockup

(Default Enabled for MAX31725; Default

 Disabled for MAX31726)

 Separate Open-Drain OS Output Operates as

 Interrupt or Comparator/Thermostat Output

RESET Input (MAX31726)

Applications

Servers

Networking

Telecom

Industrial

Typical Application Circuits

19-6477; Rev 2; 12/14

Ordering Information appears at end of data sheet.

For related parts and recommended products to use with this part, refer to: www.maximintegrated.com/MAX31725.related

MAX31725

0.1µF

+2.5V TO +3.7V

4.7kΩ

SDA

TO I

MASTER

SCL

GND

MAX31726

0.1µF

+2.5V TO +3.7V

4.7kΩ

RESET

SDA

TO I

MASTER

SCL

GND

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.

Summary of content (15 pages)

PAGE 1
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors General Description The MAX31725/MAX31726 temperature sensors accurately measure temperature and provide an overtemperature alarm/interrupt/shutdown output. These devices convert the temperature measurements to digital form using a high-resolution, sigma-delta, analog-todigital converter (ADC). Accuracy is Q0.5NC from -40NC to +105NC. Communication is through an I2C-compatible 2-wire serial interface.
PAGE 2
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors ABSOLUTE MAXIMUM RATINGS (All voltages relative to GND.) Voltage Range on VDD, SDA, SCL, A0, A1.............-0.3V to +4V Voltage Range on A2, RESET, OS............ -0.3V to (VDD + 0.3V) Input Current at Any Pin .................................................... +5mA Package Input Current .................................................... +20mA Continuous Power Dissipation (TA = +70NC) TDFN (derate 24.4mW/NC above +70NC)................1951.
PAGE 3
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors ELECTRICAL CHARACTERISTICS (continued) (VDD = 2.5V to 3.7V, TA = -55NC to +150NC, unless otherwise noted. Typical values are VDD = 3.3V, TA = +25NC.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OS Delay Depends on fault queue setting 1 6 Conversions TOS Default Temperature Factory default setting 80 80 80 NC THYST Default Temperature Factory default setting 75 75 75 NC POR Voltage Threshold 2.
PAGE 4
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors I2C AC ELECTRICAL CHARACTERISTICS (continued) (VDD = 2.5V to 3.7V, TA = -55NC to +150NC, unless otherwise noted. Typical values are VDD = 3.3V, TA = +25NC.) (Notes 3, 6) (Figure 1) PARAMETER SYMBOL CONDITIONS MIN Pulse Width of Suppressed Spike tSP (Note 10) 0 SDA Time Low for Reset of Serial Interface tTIMEOUT (Note 7) 45 TYP 50 MAX UNITS 50 ns 55 ms Note 3: Limits are 100% production tested at TA = +25NC and/or TA = +85NC.
PAGE 5
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) STATIC QUIESCENT SUPPLY CURRENT vs. TEMPERATURE 8 3.3VDD IDD (µA) 3.7VDD 900 600 6 4 300 2.5VDD 0 -20 -70 30 80 130 30 130 ACCURACY vs. TEMPERATURE (VDD = 2.5V) ACCURACY vs. TEMPERATURE (VDD = 3.3V) 0.8 ERROR (°C) MEAN ERROR 0 MAX31725 toc04 1.5 +3 SIGMA ERROR +3 SIGMA ERROR 0 -3 SIGMA ERROR -3 SIGMA ERROR -0.5 80 TEMPERATURE (°C) MAX31725 toc03 0.
PAGE 6
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Pin Configuration TOP VIEW VDD A0 8 7 A2 A1 (RESET) 6 5 MAX31725 MAX31726 EP + 1 2 3 4 SDA SCL OS GND TDFN (3mm x 3mm) ( ) MAX31726 ONLY. Pin Description PIN MAX31725 MAX31726 NAME FUNCTION 1 1 SDA Serial-Data Input/Output Line. Open drain. Connect SDA to a pullup resistor. High impedance for supply voltages from 0 to 3.7V. 2 2 SCL Serial-Data Clock Input. Open drain. Connect SCL to a pullup resistor.
PAGE 7
MAX31725/MAX31726 ±0.
PAGE 8
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Detailed Description The MAX31725/MAX31726 temperature sensors measure temperature and convert the data into digital form. An I2C-compatible two-wire serial interface allows access to conversion results. The devices accept standard I2C commands to read the data, set the overtemperature alarm (OS) trip thresholds, and configure other characteristics. While reading the temperature register, any changes in temperature are ignored until the read is completed.
PAGE 9
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Table 1a. MAX31725 Slave Address Selection SLAVE A2 A1 A0 ADDRESS CONNECTION CONNECTION CONNECTION BYTE (hex) GND GND GND 90h GND GND VDD 92h GND GND SCL 82h GND GND SDA 80h GND VDD GND 94h GND VDD VDD 96h GND VDD SCL 86h crossing above TOS and is then reset, it is asserted again only when the temperature drops below THYST. The output then remains asserted until it is reset by a read.
PAGE 10
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors be written for each I2C transaction. All registers are read and write, except for the read-only temperature register. Internal Registers The device contains four registers, each of which consists of 2 bytes. The configuration register contains only 1 byte of actual data and, when read as a 2-byte register, repeats the same data for the second byte. During a 2-byte write to the configuration register the second byte written takes precedence.
PAGE 11
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Perform a read operation by issuing the slave address byte (write), pointer byte, repeat START, another slave address byte (read), and then reading the data byte. After 2 data bytes the pointer register auto increments and, if pointing to a valid address, additional data can be read. See Figure 4. Bits D[15:0] contains the temperature data, with the LSB representing 0.00390625NC and the MSB representing the sign bit; see Table 3.
PAGE 12
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Table 4.
PAGE 13
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Table 6. Configuration Register Fault Queue Bits FAULT QUEUE [1] BIT D4 FAULT QUEUE [0] BIT D3 NUMBER OF FAULTS 0 0 1 (POR state) 0 1 2 1 0 4 1 1 6 Data Format Bit D5 selects the temperature data format for the temperature, TOS, and THYST registers. When D5 is 0 (normal format), the data format is two’s complement with a range of -128NC to +127.99609375NC. Set D5 to 1 for extended temperature format.
PAGE 14
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Ordering Information PART TEMP RANGE RESET TIMEOUT ENABLED AT POR MAX31725MTA+ -55NC to +150NC No Yes PIN-PACKAGE 8 TDFN-EP* MAX31726MTA+ -55NC to +150NC Yes No 8 TDFN-EP* +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.
PAGE 15
MAX31725/MAX31726 ±0.5°C Local Temperature Sensors Revision History REVISION NUMBER REVISION DATE 0 9/12 Initial release — 1 3/13 Added the MAX31726 All 2 12/14 Updated Benefits and Features section 1 DESCRIPTION PAGES CHANGED 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.