PCB 板接地

AD9_PCB · 发表于 2017-11-27 17:46

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大家好，狗主好：
小弟最近遇到一个问题，我先描述下产品吧。我的电路板放在一个大铁壳里面，长方形的。通过4个螺丝孔固定，板子螺丝孔没有和板子上的地连接。电源供电是一边DC头连接到电路板DC坐上，另一边接到固定在铁壳的卡龙头上，卡龙头3个角，1正，二负，3接在铁壳上，当地线接到大地上。现在客户说我的板子没接外壳。
那么问题来了：电源适配器一端DC头，2个接AC，一个接大地，适配器输出12V，你把电路板的地接到大地上，那么不就是把适配器输出的12V负端接到大地上了吗这样不会出问题？电流还是往12V负端跑啊，因为大地不可能跑到适配器的输出端的地上啊

超級狗 · 发表于 2017-11-28 21:25

六樓講的另一種接法。

Class I AC input:
This type has a three-wire input with the AC earth ground connection and provides a path to a stable reference (earth) to help minimize output common mode noise and electromagnetic interference (EMI) and immunity. Generally, this type of AC input has better performance where output electrical noise interference must be kept to a minimum. However, the availability of power sources with a ground connection may be limited or not guaranteed, and in this case, power supplies specifically designed for AC inputs without ground should be selected. Also, with a class I AC input, it is possible to provide a reference point for the load (user system) through the power supply to be ground reference for EMI and EMC performance improvements. In some applications, this is a must and provides a path to ground for ESD as well as reducing the amount of AC mains surges and electrical fast transients from reaching the load. Connecting the output to earth ground eliminates the output common mode noise.

超級狗 · 发表于 2017-11-28 21:16

Linking grounds
The link between the direct-current (DC) ground of a local electronic circuit and the earth reference potential of the mains is usually provided by the local power supply converting the line voltage into the required DC output.
Figure 1 shows a simplified block diagram of a low-cost switched-mode power supply (SMPS) typically used in personal computers, laser printers, and other equipment. Here the DC ground of the SMPS output is referenced to the protective earth (PE) conductor of the mains via the SMPS chassis. This direct link, therefore, acts as a sense conductor, establishing the PE voltage as the local DC ground potential.

guhanzuiying · 发表于 2017-11-28 09:27

你可以在板子上做出和螺丝连接或者外壳连接的大地然后通过1M电租并联高压电容和你的12V负极连接大地不要直接和负极连接

松哥无敌 · 发表于 2017-11-27 21:09

没看懂你的描述呢

flywinder · 发表于 2017-11-28 09:02

你在说啥

AD9_PCB · 发表于 2017-11-28 09:17

如图片所示

AD9_PCB · 发表于 2017-11-28 09:17

松哥无敌发表于 2017-11-27 21:094 H" Z9 M% ^) j- B; W" j+ B
没看懂你的描述呢

如图片所示

clp783 · 发表于 2017-11-28 10:28

问题看不懂，只看出那字真丑

AD9_PCB · 发表于 2017-11-28 11:15

clp783 发表于 2017-11-28 10:283 _6 C7 N6 z$ U" G- U% ]
问题看不懂，只看出那字真丑

这叫草书，另外你真看不懂？

DIY民工 · 发表于 2017-11-28 11:55

描述问题也是学问，就像别人给你解答一样，要让别人一目了然的看懂

shihaidan · 发表于 2017-11-28 12:54

板子上地接大地后，防静电会好很多。

超級狗 · 发表于 2017-11-28 21:39

Chasis Ground PCB Layout

AD9_PCB · 发表于 2017-11-29 15:32

超級狗发表于 2017-11-28 21:392 U# _$ \# \. E+ }* U% _) x
Chasis Ground PCB Layout

谢谢版主

hagelee · 发表于 2017-12-1 22:49

学习一下!

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