ltc2983-wA high-performance analog input stage incorporates low-noise, low-offset buffered A/D converters, as well as 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 LTC2983 provides a high-precision multiplexed connection to virtually any sensor. It accurately measures absolute signals on the order of microvolts from thermocouples and ratiometric resistance measurements from RTDs and thermistors, linearizes the results, and provides them in °C or °F. Up to twenty analog inputs are available, and digitized measurements can be expressed in °C or °F. The SPI interface works with virtually any digital system, and a comprehensive software support system with drop-down menus simplifies the integration of the LTC2983.
    The LTC2983 is a simple yet feature-rich device that connects to a wide variety of temperature sensors, including type B, E, J, K, N, S, R, and T thermocouples, 2-, 3-, and 4-wire RTDs, 2.25kΩ to 30kΩ thermistors, and temperature-sensing diodes. The LTC2983 operates with ground-referenced sensors without the need for amplifiers, negative sources, or level-shifting circuitry. Signals are simultaneously digitized by three high-precision 24-bit Δ∑ converters using a 10ppm/°C reference. Automatic thermocouple cold junction compensation can be performed using any type of external sensor. The chip includes linearization algorithms for the most common sensors. Custom sensors can be linearized with custom coefficients programmed on the chip. Dual programmable excitation current sources incorporate current reversal and current range adjustment to improve accuracy and reduce noise. To ensure accurate resistive measurements, current reversal eliminates thermocouple effects on the resistive sensor. Special sensor fault detection alerts the user in case of short circuit, open circuit, over-temperature, under-temperature, and A/D converter range exceedance.
    The LTC2983 is available in commercial and industrial versions and offers operating temperature ranges of 0°C to 70°C and -40°C to 85°C, respectively. The LTC2983 is now available in a RoHS-compliant 7mm x 7mm LQFP-48 package.

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