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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM

LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM
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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 1

LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM DESCRIPTION Directly Digitizes 2-, 3-, or 4-Wire RTDs, Thermocouples, Thermistors, and Diodes nn On-Chip EEPROM Stores Channel Configuration Data and Custom Coefficients nn Single 2.85V to 5.25V Supply nn 20 Flexible Inputs Allow Interchanging Sensors nn Automatic Thermocouple Cold Junction Compensation nn Built-In Standard and User-Programmable Coefficients for Thermocouples, RTDs and Thermistors nn Measures Negative Thermocouple Voltages nn Automatic Burn Out, Short-Circuit and Fault Detection nn Buffered Inputs Allow External Protection nn Simultaneous 50Hz/60Hz Rejection nn Includes 15ppm/°C (Max) Reference (I-Grade) nn The LTC 2984 measures a wide variety of temperature sensors and digitally outputs the result, in °C or °F, with 0.1°C accuracy and 0.001°C resolution. The LTC2984 can measure the temperature of virtually all standard (type B, E, J, K, N, S, R, T) or custom thermocouples, automatically compensate for cold junction temperatures and linearize the results. The device can also measure temperature with standard 2-, 3-, or 4-wire RTDs, thermistors, and diodes. It has 20 reconfigurable analog inputs enabling many sensor connections and configuration options. The LTC2984 includes excitation current sources and fault detection circuitry appropriate for each type of temperature sensor as well as an EEPROM for storing custom coefficients and channel configuration data. ® The LTC2984 allows direct interfacing to ground referenced sensors without the need for level shifters, negative supply voltages, or external amplifiers. All signals are buffered and simultaneously digitized with three high accuracy, 24-bit ∆∑ ADC's, driven by an internal 10ppm/°C (maximum) reference. APPLICATIONS Direct Thermocouple Measurements Direct RTD Measurements nn Direct Thermistor Measurements nn Custom Sensor Applications nn nn L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear 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 LINEARIZATION/ FAULT DETECTION 24-BIT ∆∑ ADC

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 3

LTC2984 ABSOLUTE MAXIMUM RATINGS LX PACKAGE 48-LEAD (7mm × 7mm) PLASTIC LQFP TJMAX = 150°C, θJA = 57°C/W ORDER INFORMATION LEAD FREE FINISH PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 4

LTC2984 COMPLETE SYSTEM ELECTRICAL CHARACTERISTICS which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. Supply Voltage Supply Current Sleep Current The l denotes the specifications UNITS Input Range All Analog Input Channels Output Rate Two Conversion Cycle Mode (Notes 6, 9) Output Rate Three Conversion Cycle Mode (Notes 6, 9) Input Common Mode Rejection Input Normal Mode Rejection Input Normal Mode Rejection Input Normal Mode Rejection Power-On Reset Threshold Analog Power-Up Digital Initialization The l denotes the specifications which apply...

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 5

LTC2984 REFERENCE ELECTRICAL CHARACTERISTICS the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER The l denotes the specifications which apply over Output Voltage Output Voltage Temperature Coefficient Output Voltage Temperature Coefficient Line Regulation Load Regulation IOUT(SINK) = 100µA Output Voltage Noise Turn-On Time Output Short-Circuit Current Long Term Drift of Output Voltage (Note 13) Hysteresis (Note 14) DIGITAL INPUTS AND DIGITAL OUTPUTS full operating temperature range, otherwise specifications are at TA = 25°C. SYMBOL The l denotes the...

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 6

The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. SYMBOL UNITS Years Cycles Programming Time Complete Transfer from RAM to EEPROM Read Time Complete Transfer EEPROM to RAM Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All voltage values are with respect to GND. Note 3: Full scale ADC error. Measurements do not include reference...

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 7

LTC2984 TYPICAL PERFORMANCE CHARACTERISTICS Type J Thermocouple Error and RMS Noise vs Temperature Type K Thermocouple Error and RMS Noise vs Temperature Type N Thermocouple Error and RMS Noise vs Temperature 0.8 Type S Thermocouple Error and RMS Noise vs Temperature Type T Thermocouple Error and RMS Noise vs Temperature 1.0 Type R Thermocouple Error and RMS Noise vs Temperature RMS NOISE ERROR –200 0 200 400 THERMOCOUPLE TEMPERATURE (°C) Type E Thermocouple Error and RMS Noise vs Temperature Type B Thermocouple Error and RMS Noise vs Temperature RTD PT-1000 Error and RMS Noise vs...

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 8

LTC2984 TYPICAL PERFORMANCE CHARACTERISTICS RTD PT-200 Error and RMS Noise vs Temperature RTD NI-120 RTD Error and RMS Noise vs Temperature RTD PT-100 Error and RMS Noise vs Temperature 0.8 RMS NOISE ERROR 0 400 RTD TEMPERATURE (°C) 2.252k Thermistor Error vs Temperature 3k Thermistor Error vs Temperature 5k Thermistor Error vs Temperature 1.0 30k Thermistor Error vs Temperature 10k Thermistor Error vs Temperature YSI-400 Thermistor Error vs Temperature 0.8

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 9

LTC2984 TYPICAL PERFORMANCE CHARACTERISTICS Diode Error and Repeatability vs Temperature NOISE (µVRMS) One Shot Conversion Current vs Temperature Channel Input Leakage Current vs Temperature Adjacent Channel Offset Error vs Input Fault Voltage Adjacent Channel Offset Error vs Input Fault Voltage (VDD = 5V)

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LTC2984 Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM - 10

LTC2984 PIN FUNCTIONS GND (Pins 1, 3, 5, 7, 9, 12, 15, 44): Ground. Connect each of these pins to a common ground plane through a low impedance connection. All eight pins must be grounded for proper operation. VDD (Pins 2, 4, 6, 8, 45): Analog Power Supply. Tie all five pins together and bypass as close as possible to the device, to ground with a 0.1μF capacitor. VREF_BYP( Pin 11): Internal Reference Power. This is an internal supply pin, do not load this pin with external circuitry. Decouple with a 0.1µF capacitor to GND. VREFOUT (Pin 13): Reference Output Voltage. Short to VREFP. A...

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