Linear Technology has introduced the LTC2983, a high performance digital temperature measurement IC which directly digitizes RTDs, thermocouples, thermistors and external diodes with 0.1°C accuracy and 0.001°C resolution. 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 linearization required for each.
The LTC2983 provides a multiplexed high precision interface to virtually any sensor. It is able to precisely measure absolute microvolt level signals from thermocouples and ratiometric resistance measurements from RTDs and thermistors, linearizes the results and outputs the results in °C or °F. Up to twenty analogue inputs are available and digitized measurements can be output in Centigrade or Fahrenheit. The SPI interface has been designed to work with virtually any digital system and a comprehensive software support system with drop-down menus allows easy customizing of the LTC2983.
Simple, but feature-rich, the LTC2983 interfaces with a wide variety of temperature sensors, including type B, E, J, K, N, S, R, T thermocouples, 2,3, or 4-wire RTDs, 2.25kO to 30kO 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 digitized with three, high accuracy, 24-bit ?S ADCs using an internal 10ppm/°C reference. Automatic thermocouple cold junction compensation can be done using any type of external sensor. Included on the chip are linearization algorithms for all common sensor types. Custom sensors can be linearized with custom coefficients programmed into the chip.
Dual programmable excitation current sources feature current reversal and current ranging to improve accuracy and reduce noise. To ensure resistive measurements are accurate, 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 LTC2983 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 LTC2983 is available in a RoHS compliant, 7mm x 7mm LQFP-48 package.