EVALUATION KIT AVAILABLE MAX31850/MAX31851 Cold-Junction Compensated, 1-Wire Thermocouple-to-Digital Converters General Description Benefits and Features The MAX31850/MAX31851 cold-junction compensat- S Integration Reduces Design Time and Lowers M ed, 1-Wire thermocouple-to-digital converters perform System Cost cold-junction compensation and digitize the signal from 14-Bit, 0.25NC Resolution a K-, J-, N-, T-, S-, R-, or E-type thermocouple. The con- Integrated Cold-Junction Compensation verters resolve temperatures to 0.25NC, allow readings Available for Multiple Thermocouples Types: as high as +1768NC and as low as -270NC, and exhibit Supports K-, J-, N-, T-, and E-Type (MAX31850) thermocouple accuracy of 8 LSBs (2NC) for temperatures S- and R-Type (MAX31851) ranging from -200NC to +700NC. Detects Thermocouple Shorts to GND or V DD Communication with the master microcontroller is over a Detects Open Thermocouple 1-Wire bus that by definition requires only one data line S 1-Wire Multiddrop Capability Simplifies (and ground) for communication. Operating power can Multisensor Systems be obtained directly from the data line (parasite power), eliminating the need for an external power supply. 1-Wire Interface (Read-Only) Power Can Be Obtained from Interface (Parasite-Powered Mode) Each device has a unique 64-bit serial code, which allows multiple units to function on the same 1-Wire bus. Applications Therefore, it is simple to use one microcontroller (the master device) to monitor temperature from many ther- Industrial HVAC mocouples distributed over a large area. Appliances Medical Four location address inputs simplify mapping of Ordering Information appears at end of data sheet. individual units to specific locations. Block Diagram DQ MAX31850 PARASITE- S5 MAX31851 POWER COLD-JUNCTION CIRCUIT COMPENSATION 64-BIT ROM AND C PP 1-Wire PORT T+ S4 ADC POWER- V SUPPLY DD T- SENSE S1 FAULT MEMORY S2 DETECTION CONTROL LOGIC S3 REFERENCE SCRATCHPAD VOLTAGE GND ADDRESS PIN INPUT AD0 AD1 AD2 AD3 1-Wire is a registered trademark of Maxim Integrated Products, Inc. For related parts and recommended products to use with this part, refer to: www.maximintegrated.com/MAX31850.related For pricing, delivery, and ordering information, please contact Maxim Direct at 19-6725 Rev 2 1/15 1-888-629-4642, or visit Maxim Integrateds website at www.maximintegrated.com.MAX31850/MAX31851 Cold-Junction Compensated, 1-Wire Thermocouple-to-Digital Converters ABSOLUTE MAXIMUM RATINGS Supply Voltage Range (V to GND) ..................-0.3V to +4.0V Operating Temperature Range ........................ -40NC to +125NC DD All Other Pins ............................................ -0.3V to (V + 0.3V) Junction Temperature .....................................................+150NC DD Continuous Power Dissipation (T = +70NC) Storage Temperature Range .......................... -65NC to +150NC A TDFN (derate 16.70mW/NC above +70NC) ...........1333.30mW Lead Temperature (soldering, 10s) ................................+300NC ESD Protection (All Pins, Human Body Model) ...................2kV 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 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. PACKAGE THERMAL CHARACTERISTICS (Note 1) TDFN Junction-to-Ambient Thermal Resistance (B ) ..........60NC/W JA Junction-to-Case Thermal Resistance (B ) ...............30NC/W 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. DC ELECTRICAL CHARACTERISTICS (T = -40NC to +125NC, unless otherwise noted.) (Note 2) A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage V Local power (Note 3, 4) 3.0 3.3 3.7 V DD Parasite power (Note 3) 3.0 3.7 Pullup Supply Voltage V V PU (Notes 3, 4) Local power (Note 3) 3.0 V DD Input Logic-Low V (Notes 4, 6) -0.3 +0.8 V IL lower of 3.7V Local power 2.2 or (V + DD 0.3V) Input Logic-High (Note 4) V V IH lower of 3.7V Parasite power 3.0 or (V + DD 0.3V) Output Sink Current I V = 0.4V (Note 4) 4.0 mA L I/O Standby Supply Current I (Notes 7, 8) 280 1000 nA DDS Active Supply Current I V = 3.7V (Note 9) 900 1750 FA DD DD DQ Input Current I (Note 10) 5 FA DQ Power-Supply Rejection -0.3 C/V Input Leakage Current (AD0AD3 Pins) (Note 3) -1 +1 FA T = -40C to +125C, 100mV across A Thermocouple Input Bias Current I -100 +100 nA BTC the thermocouple inputs (Note 3) Maxim Integrated 2