适当选择PCB与外壳接地的点的原则是什么？
[此贴子已经被admin于2009-9-6 8:53:54编辑过]
<span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">选择</span><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New="New" Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">PCB</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">与外壳接地点选择的原则是利用</span><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New="New" Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">chassis ground</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">提供低阻抗的路径给回流电流</span><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New="New" Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">(returning current)</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">及控制此回流电流的路径。例如，通常在高频器件或时钟产生器附近可以借固定用的螺丝将</span><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New="New" Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">PCB</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">的地层与</span><span lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New="New" Roman'; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">chassis ground</span><span style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: 'Times New="New" Roman'; mso-hansi-font-family: 'Times New="New" Roman'; mso-bidi-font-family: 'Times New="New" Roman'; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">做连接，以尽量缩小整个电流回路面积，也就减少电磁辐射。</span>
哦，这个样子呀
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