EVALUATION KIT AVAILABLE MAX31856 Precision Thermocouple to Digital Converter with Linearization General Description Benefits and Features The MAX31856 performs cold-junction compensation Provides High-Accuracy Thermocouple Temperature and digitizes the signal from any type of thermocouple. Readings The output data is formatted in degrees Celsius. This Includes Automatic Linearization Correction for 8 converter resolves temperatures to 0.0078125C, allows Thermocouple Types readings as high as +1800C and as low as -210C 0.15% (max, -20C to +85C) Thermocouple Full- (depending on thermocouple type), and exhibits thermo- Scale and Linearity Error couple voltage measurement accuracy of 0.15%. The 19-Bit, 0.0078125C Thermocouple Temperature thermocouple inputs are protected against overvoltage Resolution conditions up to 45V. Internal Cold-Junction Compensation Minimizes A lookup table (LUT) stores linearity correction data for System Components several types of thermocouples (K, J, N, R, S, T, E, and 0.7C (max, -20C to +85C) Cold-Junction B). Line frequency filtering of 50Hz and 60Hz is included, Accuracy as is thermocouple fault detection. A SPI-compatible inter- 45V Input Protection Provides Robust System face allows selection of thermocouple type and setup of Performance the conversion and fault detection processes. Simplifies System Fault Management and Troubleshooting Applications Detects Open Thermocouples Temperature Controllers Industrial Ovens, Furnaces, and Environmental Over- and Undertemperature Fault Detection Chambers 50Hz/60Hz Noise Rejection Filtering Improves Industrial Equipment System Performance Ordering Information appears at end of data sheet. 14-Pin TSSOP Package Typical Application Circuit AGND DGND BIAS FAULT 0.01F SDI T- MAX31856 0.1F T+ SDO 0.01F TO MICROCONTROLLER 3.3V AVDD SCK 0.1F DNC CS DRDY DVDD 3.3V 0.1F 19-7534 Rev 0 2/15MAX31856 Precision Thermocouple to Digital Converter with Linearization Absolute Maximum Ratings AVDD, DVDD........................................................-0.3V to +4.0V Operating Temperature Range ......................... -55C to +125C T+, T-, Bias ..........................................................................45V Junction Temperature ......................................................+150C T+, T-, Bias .......................................................................20mA Storage Temperature Range ........................... -65C to +150C All Other Pins .......................................-0.3V to (V + 0.3V) Lead Temperature (soldering, 10s) .................................+300C DVDD Continuous Power Dissipation (T = +70C) Soldering Temperature A TSSOP (derate 9.1mW/C above +70C) ..................727.3mW (reflow) ................See IPC/JEDEC J-STD-020A Specification ESD Protection (All pins, Human Body Model) .................2000V 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. (Note 1) Package Thermal Characteristics TSSOP Junction-to-Ambient Thermal Resistance ( ) ........110C/W Junction-to-Case Thermal Resistance ( ) ...............30C/W JA JC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Recommended DC Operating Conditions (T = -55C to +125C, unless otherwise noted.)(Notes 2 and 4) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V , AVDD Power-Supply Voltage 3.0 3.3 3.6 V V DVDD AVDD-DVDD -100 +100 mV Cable Resistance R Per lead 40 k CABLE Input Logic 0 V 0.8 V IL Input Logic 1 V 2.1 V IH Electrical Characteristics (3.0V V 3.6V, T = -55C to +125C, unless otherwise noted.)(Notes 2, 3, and 4) DD A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Standby 5.25 10 A Supply Current I DD Active conversion 1.2 2 mA 19 Bits Thermocouple Temperature Resolution 0.0078125 C Cold-Junction Temperature Data 0.015625 C Resolution T = +25C -10 +10 A T = -40C to +85C -10 +65 A Thermocouple Input Bias Current I nA TCBIAS T = -55C to +105C -20 +110 A T = -55C to +125C -20 +400 A Maxim Integrated 2 www.maximintegrated.com