主動與被動溫度傳感器：設計者需慎重選擇

　　熟悉的環境或遠程組件的臨界溫度是至關重要的許多系統和部件的品種有寬的器件可用于設計使用。然而，不是所有的溫度傳感元件的任何給定的任務是正確的和錯誤的選擇，可以在一個昂貴的準確性而言，項目進度和產品成本。

　　在這篇文章中，我們將介紹常用的被動和有源溫度傳感器的特點，包括它們的優點和局限性，以幫助您縮小組件的選擇，考慮在手的設計問題。一個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的傳感器可以幫助解決問題的多個設計等諸多領域，嵌入式計算、家電、物聯網、可穿戴設備。

　　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.