RTD接口和線性化

　　實現(xiàn)鉑電阻溫度檢測器（RTD）的極端精度要求極其精確的信號調(diào)理和處理。本文介紹了如何使用aduc706x和幾個無源元件實現(xiàn)基于RTD傳感器接口的MCU。

　　鉑電阻溫度檢測器（RTD）是測量溫度在200°C至850°C范圍內(nèi)最精確的傳感器之一。RTD能夠?qū)崿F(xiàn)校準精度為0.02°C或更好。然而，獲得最大程度的精確性需要精確的信號調(diào)理、模數(shù)轉換、線性化和校準。

　　Analog Devices，Inc.?MicroConverter產(chǎn)品系列包括一個24位的ADC和一個理想的適合于RTD傳感器信號調(diào)理電路單芯片32位ARM7微控制器設備。

　　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.