Datasheet LTC2984 (Analog Devices)

LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM
FEATURES DESCRIPTION
n Directly Digitizes 2-, 3-, or 4-Wire RTDs, The LTC®2984 measures a wide variety of temperature Thermocouples, Thermistors, and Diodes sensors and digitally outputs the result, in °C or °F, with n On-Chip EEPROM Stores Channel Configuration Data 0.1°C accuracy and 0.001°C resolution. The LTC2984 can and Custom Coefficients measure the temperature of virtually all standard (type B, n Single 2.85V to 5.25V Supply E, J, K, N, S, R, T) or custom thermocouples, automatically n 20 Flexible Inputs Allow Interchanging Sensors compensate for cold junction temperatures and linearize n Automatic Thermocouple Cold Junction Compensation the results. The device can also measure temperature with n Built-In Standard and User-Programmable Coefficients standard 2-, 3-, or 4-wire RTDs, thermistors, and diodes. for Thermocouples, RTDs and Thermistors It has 20 reconfigurable analog inputs enabling many sen- n Measures Negative Thermocouple Voltages sor connections and configuration options. The LTC2984 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 as well as an EEPROM for storing custom coefficients and n Includes 15ppm/°C (Max) Reference (I-Grade) channel configuration data. The LTC2984 allows direct interfacing to ground referenced
APPLICATIONS
sensors without the need for level shifters, negative supply n Direct Thermocouple Measurements voltages, or external amplifiers. All signals are buffered and n Direct RTD Measurements simultaneously digitized with three high accuracy, 24-bit ∆∑ n Direct Thermistor Measurements ADC's, driven by an internal 10ppm/°C (maximum) reference. n L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Custom Sensor Applications Technology Corporation. All other trademarks are the property of their respective owners. Patents Pending
TYPICAL APPLICATION Thermocouple Measurement with Automatic Cold Junction Compensation Typical Temperature Error Contribution
2.85V TO 5.25V 1k 0.5 LTC2984 0.4 0.1µF 24-BIT 0.3 1k ∆∑ ADC THERMISTOR 0.2 THERMOCOUPLE 0.1 0 LINEARIZATION/ SPI FAULT DETECTION –0.1 INTERFACE ERROR (°C) RSENSE 24-BIT 2k °C/°F –0.2 3904 DIODE ∆∑ ADC RTD –0.3 –0.4 4 3 –0.5–200 0 200 400 600 800 1000 1200 1400 PT-100 RTD 24-BIT TEMPERATURE (°C) ∆∑ ADC 2 2984 TA01b 1 VREF (10ppm/°C) EEPROM 2984 TA01a 2984fb For more information www.linear.com/LTC2984 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Complete System Electrical Characteristics ADC Electrical Characteristics Reference Electrical Characteristics Digital Inputs and Digital Outputs EEPROM Characteristics Typical Performance Characteristics Pin Functions Block Diagram Test Circuits Timing Diagram Overview Applications Information EEPROM Overview Eeprom Read/Write Validation EEPROM Write Operation EEPROM Read Operation Thermocouple Measurements Diode Measurements RTD Measurements Thermistor Measurements Supplemental Information Direct ADC Measurements Fault Protection and Anti-Aliasing 2- and 3-Cycle Conversion Modes Running Conversions Consecutively on Multiple Channels Entering/Exiting Sleep Mode MUX Configuration Delay Global Configuration Register Reference Considerations Custom Thermocouples Custom RTDs Custom Thermistors Package Description Revision History Typical Application Related Parts