主动与被动温度传感器：设计者需慎重选择

　　主动与被动温度传感器：设计者需慎重选择

　　熟悉的环境或远程组件的临界温度是至关重要的许多系统和部件的品种有宽的器件可用于设计使用。然而，不是所有的温度传感元件的任何给定的任务是正确的和错误的选择，可以在一个昂贵的准确性而言，项目进度和产品成本。

　　在这篇文章中，我们将介绍常用的被动和有源温度传感器的特点，包括它们的优点和局限性，以帮助您缩小组件的选择，考虑在手的设计问题。一个更深的下潜到最近的一些集成温度传感器IC将展示如何将这些先进的传感器可以帮助解决问题的多个设计等诸多领域，嵌入式计算、家电、物联网、可穿戴设备。

　　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.