Classification and function of land

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Classification and function of land [Copy link]

1. Signal " ground " ; DT we[G5| Signal " ground " is also called reference " ground " , which is the reference point of zero potential and the common section of the circuit signal loop. The graphic symbol is "⊥". ph * ] G 1 ) DC ground: DC circuit " ground " , zero potential reference point. GR U/ 2 ) AC ground: The neutral line of AC power. It should be distinguished from the ground line. - [1] Wc [1] x 3 ) Power ground: The zero potential reference point of high current network devices and power amplifier devices. /MiRP iy 4 ) Analog ground: The zero potential reference point of amplifiers, sample-and-hold devices, A/D converters and comparators. Xm F *. b 5 ) Digital ground: Also called logic ground, it is the zero potential reference point of digital circuits. > 6 ) " Hot ground " : The switching power supply does not need to use a transformer. The " ground " of its switching circuit is related to the mains power grid, the so-called " hot ground " , which is charged. The graphic symbol is: " " . 7 ) " Cold ground " : Since the high-frequency transformer of the switching power supply isolates the input and output ends; and since its feedback circuit often uses photoelectric coupling, it can transmit feedback signals and isolate the "ground" of both sides ; so the ground of the output end is called " cold ground " , which is not charged . The graphic symbol is " ⊥ " . 2. Protective " ground " ; Protective " ground " is a wiring method set up to protect personnel safety. One end of the protective " ground " line is connected to the electrical appliance, and the other end is reliably connected to the earth. 3. " Ground " in audio . 1 ) Shielded wire grounding: In order to prevent interference, the metal casing of the audio system is connected to the signal " ground " with a wire , which is called shielded grounding. 2 ) Audio dedicated " ground " : In order to prevent interference, professional audio equipment needs to be connected to the audio dedicated " ground " in addition to the shielded " ground " . This grounding device should be buried specially and should be connected to the corresponding grounding terminal of the isolation transformer and shielded voltage-stabilized power supply as the dedicated audio grounding point in the sound control room .

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S> K{gEfzo [ Different ground line processing methods.

4l.^J>GwW }n`8 w#BSS 1. Digital ground and analog ground should be separated; ?jD#]dS\<hIn high-demand circuits, digital ground and analog ground must be separated. Even for A/D and D /A converters, it is best to separate the two " grounds " on the same chip and connect them only at one point in the system . BPn/ " d< 2. Floating ground and grounding; [.DFI



6G8<r The floating ground of the system means that the ground wires of each part of the system circuit are floating and not connected to the ground. This connection method has a certain anti-interference ability. However, the insulation resistance between the system and the ground cannot be less than
50MΩ , once the insulation performance decreases, it will cause interference. Usually the system is floating and the chassis is grounded, which can enhance the anti-interference ability and be safe and reliable. ;b6 F[1] [1] 3.Single-point grounding;[[-#fV>V2In low-frequency circuits, the wiring and components will not have much impact. Usually, circuits with frequencies less than1MHzuse single-point grounding.e=fM\4d34.Multi-point grounding.2rv|d<F+In high-frequency circuits, parasitic capacitance and inductance have a greater impact. Usually, circuits with frequencies greater than10MHzuse multi-point grounding.

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破茧佼龙

8 Wrong

soso

At work, we always encounter interference caused by improper ground wire settings. We have supplemented the information to achieve "grounding" invincibility!


For analog circuits, the design of the ground wire is a critical link. Many circuits such as digital meters, AD/DA interface boards, etc. have a distinction between digital ground and analog ground. They are also grounded, but there are differences between the two. It can be said that the quality of the ground wire design directly affects the performance of the entire circuit board. Most of the AC noise and howling of the power amplifier are caused by unreasonable ground wire design.

There is nothing much to say about the digital ground. As long as it is connected together and can pass, it is fine.

To put it simply, the analog ground should be used as a star line as much as possible for low frequencies; except for wiring, it is best to use all high frequencies as ground. I don’t involve much high frequencies, and the following is mainly for single power supplies. For dual power supplies, the star line is centered on the middle tap of the transformer. For single power supplies, the star line is centered on the negative pole of the rectifier filter capacitor.

It is naturally best to have a separate line for all ground wires for different purposes, but this is not very realistic. So you still have to pay attention to some skills. In general, the input ground should be separated from the output ground, and the high current ground should be separated from the low current ground.

The reason is that the resistance voltage drop of the ground wire is the problem. Although they are all connected together, there is a certain voltage drop due to the different currents passing through. If this voltage drop is superimposed on the output, it may not be a big problem. But if it is superimposed on the input and then amplified by dozens or hundreds of times by the circuit, even if it is one or two millivolts, it cannot be ignored when amplified dozens or hundreds of times. So there is another simple way, which is to just thicken the ground wire, so that the resistance on the ground wire is small, and the voltage drop caused by the same current is small.

Author: Lin Shuichao

破茧佼龙

Big moderator, awesome!

icy

呵呵 板主們都很厲害的喔 佩服!! 請多關照!

iwonder

Okay, I'll collect it.

破茧佼龙

The upstairs must be awake at night...night owl

wangqingtao

When you are studying and working, you must take a break.

破茧佼龙

nonsense