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9.0pt;color:#000088'><br>
<br>
</span><span style='font-size:9.0pt;color:#000088'>同<span
lang=EN-US>DS1820</span>一样，<span lang=EN-US>DS18B20</span>也支持<span
lang=EN-US>"</span>一线总线<span lang=EN-US>"</span>接口，测量温度范围为<st1:chmetcnv
UnitName="°C" SourceValue="55" HasSpace="False" Negative="True"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>-55</span>°<span
lang=EN-US>C</span></st1:chmetcnv>～<span lang=EN-US>+<st1:chmetcnv
UnitName="°C" SourceValue="125" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on">125<span lang=EN-US><span lang=EN-US>°C</span></span></st1:chmetcnv></span>，在<span
lang=EN-US>-10</span>～<span lang=EN-US>+<st1:chmetcnv UnitName="°C"
SourceValue="85" HasSpace="False" Negative="False" NumberType="1" TCSC="0"
w:st="on">85<span lang=EN-US><span lang=EN-US>°C</span></span></st1:chmetcnv></span>范围内，精度为±<st1:chmetcnv
UnitName="°C" SourceValue=".5" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>0.5</span>°<span
lang=EN-US>C</span></st1:chmetcnv>。<span lang=EN-US>DS1822</span>的精度较差为±<st1:chmetcnv
UnitName="°C" SourceValue="2" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>2</span>°<span
lang=EN-US>C</span></st1:chmetcnv>。现场温度直接以<span lang=EN-US>"</span>一线总线<span
lang=EN-US>"</span>的数字方式传输，大大提高了系统的抗干扰性。适合于恶劣环境的现场温度测量，如：环境控制、设备或过程控制、测温类消费电子产品等。与前一代产品不同，新的产品支持<span
lang=EN-US>3V</span>～<span lang=EN-US>5.5V</span>的电压范围，使系统设计更灵活、方便。而且新一代产品更便宜，体积更小。<span
lang=EN-US><br>
<br>
</span></span><span class=style1261><span
lang=EN-US>DS18B20</span>、<span lang=EN-US>DS1822</span>的特性</span><span
lang=EN-US style='font-size:9.0pt;color:#000088'><br>
<br>
DS18B20</span><span style='font-size:9.0pt;
color:#000088'>可以程序设定<span lang=EN-US>9</span>～<span lang=EN-US>12</span>位的分辨率，精度为±<st1:chmetcnv
UnitName="°C" SourceValue=".5" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>0.5</span>°<span
lang=EN-US>C</span></st1:chmetcnv>。可选更小的封装方式，更宽的电压适用范围。分辨率设定，及用户设定的报警温度存储在<span
lang=EN-US>EEPROM</span>中，掉电后依然保存。<span lang=EN-US>DS18B20</span>的性能是新一代产品中最好的！性能价格比也非常出色！<span
lang=EN-US>DS1822</span>与<span lang=EN-US>DS18B20</span>软件兼容，是<span
lang=EN-US>DS18B20</span>的简化版本。省略了存储用户定义报警温度、分辨率参数的<span lang=EN-US>EEPROM</span>，精度降低为±<st1:chmetcnv
UnitName="°C" SourceValue="2" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>2</span>°<span
lang=EN-US>C</span></st1:chmetcnv>，适用于对性能要求不高，成本控制严格的应用，是经济型产品。 继<span
lang=EN-US>"</span>一线总线<span lang=EN-US>"</span>的早期产品后，<span
lang=EN-US>DS1820</span>开辟了温度传感器技术的新概念。<span lang=EN-US>DS18B20</span>和<span
lang=EN-US>DS1822</span>使电压、特性及封装有更多的选择，让我们可以构建适合自己的经济的测温系统。<span
lang=EN-US><br>
<br>
</span></span><b><span lang=EN-US style='font-size:11.5pt;color:red'><br>
</span></b><span class=style1171><span style='font-size:11.5pt'>一、<span
lang=EN-US>DS18B20</span>的主要特性</span></span><span lang=EN-US
style='font-size:9.0pt;color:#000088'><br>
<br>
</span><span style='font-size:9.0pt;color:#000088'> （<span lang=EN-US>1</span>）适应电压范围更宽，电压范围：<span
lang=EN-US>3.0</span>～<span lang=EN-US>5.5V</span>，在寄生电源方式下可由数据线供电<span
lang=EN-US><br>
</span> （<span lang=EN-US>2</span>）独特的单线接口方式，<span lang=EN-US>DS18B20</span>在与微处理器连接时仅需要一条口线即可实现微处理器与<span
lang=EN-US>DS18B20</span>的双向通讯<span lang=EN-US><br>
</span> （<span lang=EN-US>3</span>）<span lang=EN-US>DS18B20</span>支持多点组网功能，多个<span
lang=EN-US>DS18B20</span>可以并联在唯一的三线上，实现组网多点测温<span lang=EN-US><br>
</span> （<span lang=EN-US>4</span>）<span lang=EN-US>DS18B20</span>在使用中不需要任何外围元件，全部传感元件及转换电路集成在形如一只三极管的集成电路内<span
lang=EN-US><br>
</span> （<span lang=EN-US>5</span>）温范围－<st1:chmetcnv UnitName="℃"
SourceValue="55" HasSpace="False" Negative="False" NumberType="1" TCSC="0"
w:st="on"><span lang=EN-US>55</span>℃</st1:chmetcnv>～＋<st1:chmetcnv
UnitName="℃" SourceValue="125" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>125</span>℃</st1:chmetcnv>，在<span
lang=EN-US>-10</span>～<span lang=EN-US>+<st1:chmetcnv UnitName="℃"
SourceValue="85" HasSpace="False" Negative="False" NumberType="1" TCSC="0"
w:st="on">85<span lang=EN-US><span lang=EN-US>℃</span></span></st1:chmetcnv><span
lang=EN-US>时精度为±<st1:chmetcnv UnitName="℃" SourceValue=".5"
HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on">0.5<span
lang=EN-US><span lang=EN-US>℃</span></span></st1:chmetcnv><br>
</span></span> （<span lang=EN-US>6</span>）可编程的分辨率为<span lang=EN-US>9</span>～<span
lang=EN-US>12</span>位，对应的可分辨温度分别为<st1:chmetcnv UnitName="℃"
SourceValue=".5" HasSpace="False" Negative="False" NumberType="1" TCSC="0"
w:st="on"><span lang=EN-US>0.5</span>℃</st1:chmetcnv>、<st1:chmetcnv
UnitName="℃" SourceValue=".25" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>0.25</span>℃</st1:chmetcnv>、<st1:chmetcnv
UnitName="℃" SourceValue=".125" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>0.125</span>℃</st1:chmetcnv>和<st1:chmetcnv
UnitName="℃" SourceValue=".0625" HasSpace="False" Negative="False"
NumberType="1" TCSC="0" w:st="on"><span lang=EN-US>0.0625</span>℃</st1:chmetcnv>，可实现高精度测温<span
lang=EN-US><br>
</span> （<span lang=EN-US>7</span>）在<span lang=EN-US>9</span>位分辨率时最多在<span
lang=EN-US>93.75ms</span>内把温度转换为数字，<span lang=EN-US>12</span>位分辨率时最多在<span
lang=EN-US>750ms</span>内把温度值转换为数字，速度更快<span lang=EN-US><br>
</span> （<span lang=EN-US>8</span>）测量结果直接输出数字温度信号，以<span lang=EN-US>"</span>一线总线<span
lang=EN-US>"</span>串行传送给<span lang=EN-US>CPU</span>，同时可传送<span
lang=EN-US>CRC</span>校验码，具有极强的抗干扰纠错能力<span lang=EN-US><br>
</span> （<span lang=EN-US>9</span>）负压特性：电源极性接反时，芯片不会因发热而烧毁，但不能正常工作。<span
lang=EN-US><o:p></o:p></span></span></p>
<p align=center style='text-align:center;line-height:14.0pt'><span
class=style1171><span style='font-size:11.5pt'>二、<span lang=EN-US>DS18B20</span>的外形和内部结构</span></span><span
lang=EN-US style='font-size:9.0pt;color:#000088'><br>
<br>
DS18B20</span><span style='font-size:9.0pt;
color:#000088'>内部结构主要由四部分组成：<span lang=EN-US>64</span>位光刻<span
lang=EN-US>ROM</span>、温度传感器、非挥发的温度报警触发器<span lang=EN-US>TH</span>和<span
lang=EN-US>TL</span>、配置寄存器。<span lang=EN-US>DS18B20</span>的外形及管脚排列如下图<span
lang=EN-US>1: <o:p></o:p></span></span></p>
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<td width="45%" valign=top style='width:45.0%;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><span lang=EN-US style='font-size:9.0pt;color:#000088'><a
href="../chanp/yuanjian.htm" target="_blank"><span style='text-decoration:
none;text-underline:none'><img border=0 width=117 height=384
id="_x0000_i1036" src="ds18sy12_files/ds05.jpg"
onmousewheel="return zoom_img(event,this)"
onload="javascript:if(this.width>740)this.width=740"></span></a><a
href="../chanp/yuanjian.htm" target="_blank"><span style='text-decoration:
none;text-underline:none'><img border=0 width=101 height=309
id="_x0000_i1037" src="ds18sy12_files/DS18B201.gif"></span></a><a
href="../chanp/yuanjian.htm" target="_blank"><span style='text-decoration:
none;text-underline:none'><img border=0 width=150 height=155
id="_x0000_i1038" src="ds18sy12_files/ds06.jpg"
onmousewheel="return zoom_img(event,this)"
onload="javascript:if(this.width>740)this.width=740"></span></a><o:p></o:p></span></p>
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<tr style='mso-yfti-irow:1;mso-yfti-lastrow:yes'>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><strong><span style='font-size:10.0pt;font-family:宋体;
mso-bidi-font-family:宋体;color:#000088'>图<span lang=EN-US>1</span>： </span></strong><span
lang=EN-US style='font-size:10.0pt;color:#000088'>DS18B20</span><span
style='font-size:10.0pt;color:#000088'>外形及引脚排列图<span lang=EN-US><o:p></o:p></span></span></p>
</td>
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</div>
<p align=center style='text-align:center;line-height:14.0pt'><span
lang=EN-US style='font-size:9.0pt;color:#000088'> <o:p></o:p></span></p>
<p align=center style='text-align:center;line-height:14.0pt'><strong><span
lang=EN-US style='font-size:9.0pt;font-family:宋体;mso-bidi-font-family:
宋体;color:#000088'>DS18B20</span></strong><strong><span style='font-size:
9.0pt;font-family:宋体;mso-bidi-font-family:宋体;color:#000088'>引脚定义： </span></strong><span
lang=EN-US style='font-size:9.0pt;color:#000088'><o:p></o:p></span></p>
<p align=center style='text-align:center;line-height:14.0pt'><span
lang=EN-US style='font-size:9.0pt;color:#000088'> (1)DQ</span><span
style='font-size:9.0pt;color:#000088'>为数字信号输入<span lang=EN-US>/</span>输出端；<span
lang=EN-US> <br>
(2)GND</span>为电源地；<span lang=EN-US> <br>
(3)VDD</span>为外接供电电源输入端（在寄生电源接线方式时接地）。 <span
lang=EN-US><o:p></o:p></span></span></p>
<div align=center>
<table class=MsoNormalTable border=0 cellpadding=0 style='mso-cellspacing:
1.5pt'>
<tr style='mso-yfti-irow:0;mso-yfti-firstrow:yes'>
<td width="45%" valign=top style='width:45.0%;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><span lang=EN-US style='font-size:9.0pt;color:#000088'><img
border=0 width=506 height=228 id="_x0000_i1039"
src="ds18sy12_files/ds07.jpg"><o:p></o:p></span></p>
</td>
</tr>
<tr style='mso-yfti-irow:1;mso-yfti-lastrow:yes'>
<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><strong><span style='font-size:10.0pt;font-family:宋体;
mso-bidi-font-family:宋体;color:#000088'>图<span lang=EN-US>2</span>： </span></strong><span
lang=EN-US style='font-size:10.0pt;color:#000088'>DS18B20</span><span
style='font-size:10.0pt;color:#000088'>内部结构图<span lang=EN-US><o:p></o:p></span></span></p>
</td>
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</table>
</div>
<p class=style117 align=center style='text-align:center;line-height:14.0pt'>三、<span
lang=EN-US>DS18B20</span>工作原理</p>
<p align=center style='text-align:center;line-height:14.0pt'><span
lang=EN-US style='font-size:9.0pt;color:#000088'> DS18B20</span><span
style='font-size:9.0pt;color:#000088'>的读写时序和测温原理与<span lang=EN-US>DS1820</span>相同，只是得到的温度值的位数因分辨率不同而不同，且温度转换时的延时时间由<span
lang=EN-US>2s</span>减为<span lang=EN-US>750ms</span>。<span lang=EN-US>
DS18B20</span>测温原理如图<span lang=EN-US>3</span>所示。图中低温度系数晶振的振荡频率受温度影响很小，用于产生固定频率的脉冲信号送给计数器<span
lang=EN-US>1</span>。高温度系数晶振随温度变化其振荡率明显改变，所产生的信号作为计数器<span lang=EN-US>2</span>的脉冲输入。计数器<span
lang=EN-US>1</span>和温度寄存器被预置在－<st1:chmetcnv UnitName="℃" SourceValue="55"
HasSpace="False" Negative="False" NumberType="1" TCSC="0" w:st="on"><span
lang=EN-US>55</span>℃</st1:chmetcnv>所对应的一个基数值。计数器<span lang=EN-US>1</span>对低温度系数晶振产生的脉冲信号进行减法计数，当计数器<span
lang=EN-US>1</span>的预置值减到<span lang=EN-US>0</span>时，温度寄存器的值将加<span
lang=EN-US>1</span>，计数器<span lang=EN-US>1</span>的预置将重新被装入，计数器<span
lang=EN-US>1</span>重新开始对低温度系数晶振产生的脉冲信号进行计数，如此循环直到计数器<span lang=EN-US>2</span>计数到<span
lang=EN-US>0</span>时，停止温度寄存器值的累加，此时温度寄存器中的数值即为所测温度。图<span lang=EN-US>3</span>中的斜率累加器用于补偿和修正测温过程中的非线性，其输出用于修正计数器<span
lang=EN-US>1</span>的预置值。<span lang=EN-US><o:p></o:p></span></span></p>
<div align=center>
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1.5pt'>
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<td width="45%" valign=top style='width:45.0%;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><strong><span style='font-size:9.0pt;font-family:宋体;mso-bidi-font-family:
宋体;color:#000088'>图<span lang=EN-US>3</span>：</span></strong><span
lang=EN-US style='font-size:9.0pt;color:#000088'> DS18B20</span><span
style='font-size:9.0pt;color:#000088'>测温原理框图 <span lang=EN-US><o:p></o:p></span></span></p>
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<td valign=top style='padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><span lang=EN-US style='font-size:10.0pt;color:#000088'><img
border=0 width=293 height=158 id="_x0000_i1040"
src="ds18sy12_files/ds10.gif"><o:p></o:p></span></p>
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<p align=center style='text-align:center;line-height:14.0pt'><strong><span
lang=EN-US style='font-size:9.0pt;font-family:宋体;mso-bidi-font-family:
宋体;color:#000088'>DS18B20</span></strong><strong><span style='font-size:
9.0pt;font-family:宋体;mso-bidi-font-family:宋体;color:#000088'>有<span
lang=EN-US>4</span>个主要的数据部件： </span></strong><span lang=EN-US
style='font-size:9.0pt;color:#000088'><o:p></o:p></span></p>
<p align=center style='text-align:center;line-height:14.0pt'><span
lang=EN-US style='font-size:9.0pt;color:#000088'> </span><span
style='font-size:9.0pt;color:#000088'>（<span lang=EN-US>1</span>）光刻<span
lang=EN-US>ROM</span>中的<span lang=EN-US>64</span>位序列号是出厂前被光刻好的，它可以看作是该<span
lang=EN-US>DS18B20</span>的地址序列码。<span lang=EN-US>64</span>位光刻<span
lang=EN-US>ROM</span>的排列是：开始<span lang=EN-US>8</span>位（<span lang=EN-US>28H</span>）是产品类型标号，接着的<span
lang=EN-US>48</span>位是该<span lang=EN-US>DS18B20</span>自身的序列号，最后<span
lang=EN-US>8</span>位是前面<span lang=EN-US>56</span>位的循环冗余校验码（<span
lang=EN-US>CRC=X8+X5+X4+1</span>）。光刻<span lang=EN-US>ROM</span>的作用是使每一个<span
lang=EN-US>DS18B20</span>都各不相同，这样就可以实现一根总线上挂接多个<span lang=EN-US>DS18B20</span>的目的。
<span lang=EN-US><o:p></o:p></span></span></p>
<p align=center style='text-align:center;line-height:14.0pt'><span
lang=EN-US style='font-size:9.0pt;color:#000088'> </span><span
style='font-size:9.0pt;color:#000088'>（<span lang=EN-US>2</span>）<span
lang=EN-US>DS18B20</span>中的温度传感器可完成对温度的测量，以<span lang=EN-US>12</span>位转化为例：用<span
lang=EN-US>16</span>位符号扩展的二进制补码读数形式提供，以<st1:chmetcnv UnitName="℃"
SourceValue=".0625" HasSpace="False" Negative="False" NumberType="1"
TCSC="0" w:st="on"><span lang=EN-US>0.0625</span>℃</st1:chmetcnv><span
lang=EN-US>/LSB</span>形式表达，其中<span lang=EN-US>S</span>为符号位。 <span
lang=EN-US><o:p></o:p></span></span></p>
<div align=center>
<table class=MsoNormalTable border=0 cellpadding=0 style='mso-cellspacing:
1.5pt'>
<tr style='mso-yfti-irow:0;mso-yfti-firstrow:yes'>
<td width="45%" valign=top style='width:45.0%;padding:.75pt .75pt .75pt .75pt'>
<p class=MsoNormal align=center style='text-align:center;line-height:
14.0pt'><strong><span style='font-size:10.0pt;font-family:宋体;
mso-bidi-font-family:宋体;color:#000088'>表<span lang=EN-US>1:</span></span></strong><span
class=style1101><span lang=EN-US style='font-size:10.0pt;color:#000088'>
DS18B20</span></span><span class=style1101><span style='font-size:10.0pt;
color:#000088'>温度值格式表</span></span><span lang=EN-US style='font-size:
9.0pt;color:#000088'><o:p></o:p></span></p>
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<tr style='mso-yfti-irow:1;mso-yfti-lastrow:yes'>
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