LTC2984_15 Datasheet, PDF (1/78 Pages) Linear Technology – Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM

LTC2984
FEATURES
Multi-Sensor High
Accuracy Digital Temperature
Measurement System with EEPROM
DESCRIPTION
nn _{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)}
APPLICATIONS
nn _{Direct Thermocouple Measurements}
nn _{Direct RTD Measurements}
nn _{Direct Thermistor Measurements}
nn _{Custom Sensor Applications}
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 sen-
sor 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.
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
2.85V TO 5.25V
1k
0.1µF
1k
24-BIT
∆∑ ADC
LTC2984
R_SENSE
2k
43
PT-100
RTD
2
1
24-BIT
∆∑ ADC
LINEARIZATION/
FAULT DETECTION
SPI
INTERFACE
°C/°F
24-BIT
∆∑ ADC
V_REF (10ppm/°C)
EEPROM
2984 TA01a
For more information www.linear.com/LTC2984
Typical Temperature Error
Contribution
0.5
0.4
0.3
THERMISTOR
0.2
THERMOCOUPLE
0.1
0
–0.1
–0.2
3904 DIODE
RTD
–0.3
–0.4
–0.5
–200 0
200 400 600 800 1000 1200 1400
TEMPERATURE (°C)
2984 TA01b
2984f
1