基准电压——Reference voltage

<wbr><p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">基准电压是指传感器置于<span lang="EN-US">0℃</span>的温场（冰水混合物），在通以工作电流（<span lang="EN-US">100μA</span>）的条件下，传感器上的电压值。实际上就是<span lang="EN-US">0</span>点电压。其表示符号为<span lang="EN-US">V</span>（<span lang="EN-US">0</span>），该值出厂时标定，由于传感器的温度系数<span lang="EN-US">S</span>相同，则只要知道基准电压值<span lang="EN-US">V</span>（<span lang="EN-US">0</span>），即可求知任何温度点上的传感器电压值，而不必对传感器进行分度。其计算公式为：<span lang="EN-US"> </span></span></p> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">　　<span lang="EN-US">V</span>（<span lang="EN-US">T</span>）<span lang="EN-US">=V</span>（<span lang="EN-US">0</span>）<span lang="EN-US">+S×T </span>（其特性曲线如下图）<span lang="EN-US"> </span></span></p> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span lang="EN-US" style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt"><a target="_blank" title="查看图片" href="http://baike.baidu.com/albums/2127779/2127779/0/0.html#0%24cdfe7281463bc9efbc3e1ece" rel="nofollow"><span style="font-size:1pt; color:#136ec2; text-decoration:none"></span></a><a target="_blank" href="http://baike.baidu.com/albums/2127779/2127779/0/0.html#0%24cdfe7281463bc9efbc3e1ece" rel="nofollow"><span style="color:#136ec2; text-decoration:none"> </span></a></span></p> <div><img src="https://img-blog.youkuaiyun.com/20131005223057062?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvdTAxMTM0OTY2NA==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt=""></div> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> </p> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">特性曲线<span lang="EN-US"></span></span></p> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">　　示例：如基准电压<span lang="EN-US">V</span>（<span lang="EN-US">0</span>）<span lang="EN-US">=700mV</span>；温度系数<span lang="EN-US">S=-2mV/℃</span>，则在<span lang="EN-US">50℃</span>时，传感器的输出电压<span lang="EN-US">V</span>（<span lang="EN-US">50</span>）<span lang="EN-US">=700—2×50=600</span>（<span lang="EN-US">mV</span>）。这一点正是线性温度传感器优于其它温度传感器的可贵之处。<span lang="EN-US"> </span></span></p> <p align="left" style="background:#fafafa; margin:0cm 0cm 0pt; line-height:18pt; text-align:left"> <span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">　　电压基准与系统有关。在要求绝对测量的应用场合，其准确度受使用基准值的准确度的限制。但是在许多系统中稳定性和重复性比绝对精度更重要；而在有些数据采集系统中电压基准的长期准确度几乎完全不重要，但是如果从有噪声的系统电源中派生基准就会引起误差。单片隐埋齐纳基准<span lang="EN-US">(</span>如<span lang="EN-US">AD588</span>和<span lang="EN-US">AD688)</span>在<span lang="EN-US">10 V</span>时具有<span lang="EN-US">1 mV</span>初始准确度<span lang="EN-US">(0.01 %</span>或<span lang="EN-US">100 ppm)</span>， 温度系数为<span lang="EN-US">1.5 ppm/°C</span>。这种基准用于未调整的<span lang="EN-US">12</span>位系统中有足够的准确度<span lang="EN-US">(1 LSB=244 ppm)</span>，但还不能用于<span lang="EN-US">14</span>或<span lang="EN-US">16</span>位系统。如果初始误差调整到零，在限定的温度范围内可用于<span lang="EN-US">14</span>位和<span lang="EN-US">16</span>位系统<span lang="EN-US">(AD588</span>或<span lang="EN-US">AD688</span>限定<span lang="EN-US">40℃</span>温度变化范围，<span lang="EN-US">1 LSB=61 ppm)</span>。<span lang="EN-US"> </span></span></p> <p style="margin:0cm 0cm 0pt; text-indent:26.25pt"><span style="font-size:12pt; font-family:宋体; letter-spacing:0.4pt">对于要求更高的绝对精度，基准的温度需要用一个恒温箱来稳定，并对照标准校准。在许多系统中，<span lang="EN-US">12</span>位绝对精度是不需要这样做的，只有高于<span lang="EN-US">12</span>位分辨率才可能需要。对于准确度较低<span lang="EN-US">(</span>价格也会降低<span lang="EN-US">)</span>的应用，可以使用带隙基准。</span></p> <wbr><br></wbr></wbr>