The LTC2984 is based on Linear Technology's LTC2983 and adds EEPROM (electrically erasable programmable read-only memory) to store user configuration data and custom sensor coefficients. This eliminates the need for IC or sensor programming via a host processor and facilitates the use of standalone temperature sensing boards or modules. The LTC2984's footprint and software are compatible with the LTC2983. The LTC2984's non-volatile memory simplifies designs and increases reliability in modular sensor systems.
The LTC2984 incorporates all the features of the LTC2983, plus EEPROM. A high-performance analog input stage features low-noise, low-offset buffered A/D converters and all the necessary excitation and control circuitry for each sensor. Measurements are performed under the control of a digital engine that combines all the algorithms and linearization required for each sensor. The LTC2984 provides a high-precision multiplexed interface for virtually any sensor. It accurately measures absolute microvolt signals from thermocouples and proportional resistance measurements from RTDs and thermistors, linearizes the results, and displays them in °C or °F. Up to twenty analog inputs are available, and digitized measurements can be provided in Celsius or Fahrenheit. The SPI interface works with virtually any digital system, and a comprehensive software support system with drop-down menus makes customizing the LTC2984 easy.
Simple yet feature-rich, the LTC2984 connects to a wide variety of temperature sensors, including type B, E, J, K, N, S, R, and T thermocouples, 2-, 3-, or 4-wire RTDs, 2.25 kΩ to 30 kΩ thermistors, and temperature-sensing diodes. The LTC2984 works with ground-referenced sensors without the need for amplifiers, negative power supplies, or level adjustment circuitry. Signals can be simultaneously digitized using three high-precision 24-bit Δ∑ A/D converters with an internal reference of 15 ppm/°C. Automatic thermocouple cold junction compensation can be performed using any type of external sensor. The chip integrates linearization algorithms for all common sensor types. Custom sensors can be linearized using custom coefficients programmed and stored on the chip. The two programmable excitation current sources incorporate current reversal and current reference to improve accuracy and reduce noise. To ensure the accuracy of resistive measurements, current reversal eliminates thermocouple effects on the resistive sensor. Sensor-specific fault detection alerts the user to short circuits, open circuits, over-temperature, under-temperature, and A/D converter out-of-range conditions.
The LTC2984 is available in commercial and industrial versions with temperature ranges of 0°C to 70°C and -40°C to 85°C, respectively. The LTC2984 is also available in a RoHS-compliant, 48-pin (7mm x 7mm) LQFP package.

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