RTD接口和线性化

　　RTD接口和线性化

　　实现铂电阻温度检测器（RTD）的极端精度要求极其精确的信号调理和处理。本文介绍了如何使用aduc706x和几个无源元件实现基于RTD传感器接口的MCU。

　　铂电阻温度检测器（RTD）是测量温度在200°C至850°C范围内最精确的传感器之一。RTD能够实现校准精度为0.02°C或更好。然而，获得最大程度的精确性需要精确的信号调理、模数转换、线性化和校准。

　　Analog Devices，Inc.®MicroConverter产品系列包括一个24位的ADC和一个理想的适合于RTD传感器信号调理电路单芯片32位ARM7微控制器设备。

　　This application note describes how to implement a complete RTD sensor interface using the ADuC706x and several passive components. This application note is based on the AN-709 Application Note， RTD Interfacing and Linearization using an ADuC8xx MicroConverter.

　　The software utilities and sample code referenced in this application note are highly recommended for implementing a MicroConverter-based RTD sensor interface. These utilities and code are available at www.analog.com/MicroConverter.

　　Hardware design

　　An RTD is a sensor with a resistance that varies as a function of temperature in a precisely defined manner. Before attempting to understand the details of the RTD transfer function of resistance to temperature （which is nonlinear）， assume that the nonlinearities are corrected digitally. Then， concentrate on converting the RTD resistance to a digital value. A common way to do this is shown in Figure 1.