主動(dòng)與被動(dòng)溫度傳感器：設(shè)計(jì)者需慎重選擇

　　熟悉的環(huán)境或遠(yuǎn)程組件的臨界溫度是至關(guān)重要的許多系統(tǒng)和部件的品種有寬的器件可用于設(shè)計(jì)使用。然而，不是所有的溫度傳感元件的任何給定的任務(wù)是正確的和錯(cuò)誤的選擇，可以在一個(gè)昂貴的準(zhǔn)確性而言，項(xiàng)目進(jìn)度和產(chǎn)品成本。

　　在這篇文章中，我們將介紹常用的被動(dòng)和有源溫度傳感器的特點(diǎn)，包括它們的優(yōu)點(diǎn)和局限性，以幫助您縮小組件的選擇，考慮在手的設(shè)計(jì)問題。一個(gè)更深的下潛到最近的一些集成溫度傳感器IC將展示如何將這些先進(jìn)的傳感器可以幫助解決問題的多個(gè)設(shè)計(jì)等諸多領(lǐng)域，嵌入式計(jì)算、家電、物聯(lián)網(wǎng)、可穿戴設(shè)備。

　　Sensor types

　　The thermistor （from： therm-ally sensitive res-istor） is a resistor with properties that enhance its change of resistance with temperature. Negative temperature coefficient （NTC） versions， which have lower resistance at higher temperatures， are the most common but they also come in positive temperature coefficient （PTC） flavors. They are made from a ceramic semiconductor material and are designed to have fast response times， high accuracy and good repeatability.

　　However， they are non-linear devices with an exponential change with temperature and there is a tradeoff between linear range and accuracy. When an NTC thermistor is connected in a resistor divider arrangement， as shown in Figure 1， the resulting current is linearized and Vout varies linearly with temperature over a limited range （typically about 60°C）。 If R2 is chosen to be equal to the thermistor resistance at +25°， then the output will be symmetrical around the +25°C point.