LTC2983 Multi-Sensor High Accuracy Digital Temperature Measurement System FEATURES DESCRIPTION n Directly Digitize RTDs, Thermocouples, Thermistors The LTC 2983 measures a wide variety of temperature and Diodes sensors and digitally outputs the result, in C or F, with n Single 2.85V to 5.25V Supply 0.1C accuracy and 0.001C resolution. The LTC2983 can n Results Reported in C or F measure the temperature of virtually all standard (type B, n 20 Flexible Inputs Allow Interchanging Sensors E, J, K, N, S, R, T) or custom thermocouples, automatically n Automatic Thermocouple Cold Junction Compensation compensate for cold junction temperatures and linearize n Built-In Standard and User-Programmable Coefficients the results. The device can also measure temperature with for Thermocouples, RTDs and Thermistors standard 2-, 3- or 4-wire RTDs, thermistors and diodes. It n Configurable 2-, 3- or 4-Wire RTD Configurations has 20 reconfigurable analog inputs enabling many sen- n Measures Negative Thermocouple Voltages sor connections and configuration options. The LTC2983 n Automatic Burn Out, Short-Circuit and Fault Detection includes excitation current sources and fault detection n Buffered Inputs Allow External Protection circuitry appropriate for each type of temperature sensor. n Simultaneous 50Hz/60Hz Rejection The LTC2983 allows direct interfacing to ground referenced n Includes 15ppm/C (Max) Reference (I-Grade) sensors without the need for level shifters, negative supply voltages, or external amplifiers. All signals are buffered and APPLICATIONS simultaneously digitized with three high accuracy, 24-bit n Direct Thermocouple Measurements ADCs, driven by an internal 15ppm/C (maximum) reference. n Direct RTD Measurements L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear n Direct Thermistor Measurements Technology Corporation. All other trademarks are the property of their respective owners. n Patents Pending Custom Sensor Applications TYPICAL APPLICATION Thermocouple Measurement with Automatic Cold Junction Compensation Typical Temperature Error Contribution 2.85V TO 5.25V 0.5 1k LTC2983 0.4 0.1F 0.3 24-BIT THERMISTOR 1k ADC 0.2 THERMOCOUPLE 0.1 0 0.1 LINEARIZATION/ SPI 3904 DIODE 0.2 FAULT DETECTION INTERFACE RTD R SENSE 24-BIT 0.3 2k C/F ADC 0.4 0.5 200 200 400 600 800 1000 1200 1400 0 4 3 TEMPERATURE (C) 2983 TA01b PT-100 24-BIT RTD ADC 2 1 V (10ppm/C) REF 2983 TA01a 2983fc 1 For more information www.linear.com/LTC2983 ERROR (C)LTC2983 TABLE OF CONTENTS Features ............................................................................................................................ 1 Applications ....................................................................................................................... 1 Typical Application ............................................................................................................... 1 Description......................................................................................................................... 1 Absolute Maximum Ratings ..................................................................................................... 3 Order Information ................................................................................................................. 3 Complete System Electrical Characteristics .................................................................................. 3 Pin Configuration ................................................................................................................. 3 ADC Electrical Characteristics .................................................................................................. 4 Reference Electrical Characteristics ........................................................................................... 4 Digital Inputs and Digital Outputs .............................................................................................. 5 Typical Performance Characteristics .......................................................................................... 6 Pin Functions ...................................................................................................................... 9 Block Diagram ....................................................................................................................10 Test Circuits ......................................................................................................................11 Timing Diagram ..................................................................................................................11 Overview ..........................................................................................................................12 Applications Information .......................................................................................................16 Thermocouple Measurements .............................................................................................................................. 21 Diode Measurements ............................................................................................................................................ 24 RTD Measurements .............................................................................................................................................. 28 Thermistor Measurements .................................................................................................................................... 43 Direct ADC Measurements .................................................................................................................................... 55 Supplemental Information ......................................................................................................55 Fault Protection and Anti-Aliasing ......................................................................................................................... 57 2- and 3-Cycle Conversion Modes ........................................................................................................................ 57 Running Conversions Consecutively on Multiple Channels ................................................................................... 58 MUX Configuration Delay ...................................................................................................................................... 58 Global Configuration Register ............................................................................................................................... 59 Custom Thermocouples .........................................................................................................59 Custom RTDs .....................................................................................................................62 Custom Thermistors .............................................................................................................65 Package Description ............................................................................................................70 Revision History .................................................................................................................71 Typical Application ..............................................................................................................72 Related Parts .....................................................................................................................72 2983fc 2 For more information www.linear.com/LTC2983