The LTC2984 is a high performance digital temperature measurement IC that directly digitises RTDs, thermocouples, thermistors and external diodes with 0.1°C conformity and 0.001°C resolution. It can measure the temperature of virtually all standard (type B, E, J, K, N, S, R and T) or custom thermocouples, automatically compensate for cold junction temperatures and linearise the results.
The device can also measure temperature with standard 2-, 3-, or 4-wire RTDs, thermistors, and diodes. It has 20 reconfigurable analogue inputs enabling many sensor connections and configuration options and includes excitation current sources and fault detection circuitry appropriate for each type of temperature sensor.
The LTC2984 from Linear Technology 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. It builds on Linear Technology’s LTC2983 device by adding EEPROM (electrically erasable programmable read-only memory) that stores user configuration data and custom sensor coefficients.
This addition eliminates any IC or sensor programming by a host processor and facilitates the use of self-contained temperature sensing boards or modules. The LTC2984 is pin and software compatible with the LTC2983. The non-volatile memory in this device results in simplified designs and increased reliability for modular and custom sensor systems.
The LTC2984 includes all of the features found on the LTC2983, plus EEPROM. A high performance analogue front end combines low noise and low offset buffered ADCs with all the necessary excitation and control circuits for each sensor. Measurements are performed under the control of a digital engine combining all the algorithms and linearisation required for each.
This digital temperature measurement IC provides a multiplexed high precision interface to virtually any sensor. It precisely measures absolute microvolt level signals from thermocouples and ratiometric resistance measurements from RTDs and thermistors, linearises the results and outputs them in °C or °F. Up to twenty analogue inputs are available and digitised measurements can be output in Centigrade or Fahrenheit. The SPI interface works with virtually any digital system and a comprehensive software support system with drop-down menus allowing easy customisation of this device.
The simple, feature-rich LTC2984 interfaces with a wide variety of temperature sensors, including type B, E, J, K, N, S, R and T thermocouples, 2-, 3-, or 4-wire RTDs, 2.25k? to 30k? thermistors and temperature sensing diodes. It works with ground referenced sensors without the need for amplifiers, negative supplies, or level shift circuitry. Signals are simultaneously digitised with three, high accuracy, 24-bit ?S ADCs, using an internal 15ppm/°C reference. Automatic thermocouple cold junction compensation can be done using any type of external sensor.
Included on-chip are linearisation algorithms for all common sensor types. Custom sensors can be linearised with custom coefficients programmed and stored in the chip. Dual programmable excitation current sources feature current reversal and current ranging to improve accuracy and reduce noise. To ensure accuracy of resistive measurements, current reversal eliminates thermocouple effects in the resistive sensor. Sensor specific fault detection alerts the user of short circuits, open circuits, over-temperature, under-temperature and ADC over-ranging.
The LTC2984 is offered in commercial and industrial versions, supporting operating temperature ranges from 0°C to 70°C and –40°C to 85°C, respectively. The device is available in a RoHS-compliant, 7mm x 7mm LQFP 48-lead package. Pricing starts at $21.43 each in 1,000 piece quantities.
The USA list pricing shown is for budgetary use only. International prices may differ due to local duties, taxes, fees and exchange rates.
For more information, visit www.linear.com/product/LTC2984.
Summary of Features of the LTC2984:
- Directly Digitize RTDs, Thermocouples, Thermistors & Diodes
- On-Chip EEPROM Stores Channel Configuration Data & Custom Coefficients
- Single 2.85V to 5.25V Supply
- 20 Flexible Inputs Enable Multiple Sensor Types
- Automatic Thermocouple Cold Junction Compensation
- Standard & User-Programmable Coefficients for Linearizing Thermocouples, RTDs & Thermistors
- Configurable 2-, 3-, 4-Wire RTD Configurations
- Measures Negative Thermocouple Voltages without a Negative Supply
- Automatic Burn Out, Short-Circuit & Fault Detection
- Buffered Inputs Allow External Protection & Direct Interface to Resistive Sensors
- Simultaneous 50Hz/60Hz Rejection
- Includes 15ppm/°C (Max) Reference
- 48-Lead 7mm x 7mm LQFP Package
Typical Application
Applications
- Direct Thermocouple Measurements
- Direct RTD Measurements
- Direct Thermistor Measurements
- Custom Sensor Applications
Linear Technology (UK) Limited
Tel: +44 (0)1628 477066
E-mail: uksales@linear.com
Web site: www.linear.com
Website for product information: http://www.linear.com/product/LTC2984
