Switching Power Supply PCB Layout
This post is the first in a series about PCB Layout for Power Supply unit. This part is mainly about the details that you need to know and use before starting the PCB layout (hereinafter, the abbreviation PCB will be encountered), the second part will mainly be about the design of the printed circuit boards themselves and post processing.
Bradboards are great for prototyping and are a very useful tool, but when you need to do something really serious, you can’t do without knowing how to actually make your PCB.
PCB creation is not an easy task, but a little persistence and time, and this guide will help you create your first PC.
Anatomy of the PP for PCB Layout for Power Supply Unit
When you work at your computer, any task seems abstract, but do not forget that you are working with real physical environments and materials. Before starting to study the design of boards, it would be nice to understand how they are actually made.
Cross Section to show inner layers
If you are already familiar with what and how is done, you can safely proceed to the next section.
Materials for PP
First, let’s take a look at what materials are used for manufacturing. The PCB base is made of solid non-conductive material. This material is covered with a layer of copper (or other metal), which forms the conductive layer.
Typically, the backing is fiberglass, known as FR-4. This is the most frequently used material in PCB Layout for Power Supply unit because it is fire resistant, cheap and most importantly has a low intrinsic conductivity.
For high performance (RF) circuits, other types of materials are used, such as ceramics or PTFE. For the purposes of these articles, we will not deal with high frequency circuits. When you send your PCB design to production or make your own PCB, electrical connections are usually made by removing selected sections of copper from the common conductor layer.
PCB Layout for Power Supply Unit Layers
The cheapest PCB option is a one-sided PCB, i.e. on fiberglass, only one layer of copper is used. If you are going to make a PCB at home, it will most likely be a one-sided PCB. Single-layer PCBs are very easy to manufacture and develop, but if the layout of your board does not fit into one layer, you will have to use external jumpers for electrical connections, and this may already be inconvenient at the stage of installing radio components.
Most commercial and hobby projects are based on double layer PCBs. Their use allows the development of more complex and elegant solutions for board designs.
The more complex the structures become, the more additional metallization layers the PCB requires. Usually two layers are enough and if there is no need to add more layers, then it is better not to do this, because multilayer boards are much more expensive to manufacture.
As already mentioned above, copper tracks (electrical connections) are created by removing excess copper from the surface of the metallized layer. More details about the important aspects of electrical connections will be discussed in the other article.
One of the main components of the PCB is vias, used in two and multilayer boards to electrically connect one metallization layer to another.
Vias are of several types:
1. Through vias – the most commonly used type, a hole is drilled through the entire board and plated to create electrical contact with the layers.
2. Blind (blind vias) – holes connecting the outer layer with one or more inner layers.
3. Hidden (buried vias) – vias that do not go out and connect the signals on the inner layers.
4. Micro via or Via – micro-holes or holes of small diameter and shallow depth, made by laser or drilling with depth control and connecting the outer layer to the inner layer.
That’s basically all there is to know about vias.
Other Things in PCB Layout for Power Supply Unit
Let’s look at a few more concepts for building printed circuit boards and touch on some other PCB layers, the purpose of which needs to be understood.
1. Soldermask (Soldermask) – if you ask any person what a board is, he will say that it is something green. This green is the solder mask that protects the PCB and prevents solder paste from getting on unwanted electrical pins on the board. And by the way, it is not necessarily green, but almost any color, it all depends on the manufacturer of the boards.
2. Fiducials Is a special marking on the board that allows automatic component mounting systems to calibrate and correctly install elements on the board during mounting. They are small circles of metal, not covered with a solder mask.
3. Silkscreen – This is another layer in that is applied to the PCB Layout for Power Supply unit board during production. Silk-screen printing is drawings on the board that give hints to the user, identify the component on the board by placement or denomination, and other information.
4. Copper fill – copper areas that are electrically connected to ground or power, the creation of polygons is a very important part in PCB design. Polygons reduce the noise of the device, remove excess heat from powerful active components.
Before considering board design or device circuitry, you must have an idea of what you want to design. Those. you just need to think about what you want to assemble and choose the right components for this.
Define Your Goals for PCB Layout for Power Supply Unit
The first step to successful device design is having well-defined goals for what you want in the end. You should always set smart goals for your project, which means:
-Limited in time
For example, I started working on a personal project for my own needs. The bathroom light in my apartment is dim in the evening, but when I turn on the artificial lighting, the light is quite bright and not comfortable. It would be possible to buy a lamp of lower power, but let’s say they are not on sale or there is nowhere less. And I decide to make my own lamp, which will change color and brightness and be controlled wirelessly.
Sounds pretty cool. Until the idea gets out of my head, we sit down at the computer and start planning. At this stage, my goals are very broad:
– The lamp should be multi
– Color – dimmable
None of these goals are project specific. What is meant by multicolor? Two, three or any number of colors? What is dimmable? How to wirelessly control? Wifi, Zigbee, Bluetooth or maybe voice? All methods are possible.
Let’s reformulate our goals a bit to make them smart:
– Continuously dimmable high brightness RGB LEDs, covered with acrylic coating for even light diffusion.
– Brightness control that will allow me to choose any brightness from completely off to maximum brightness of the LEDs.
– Bluetooth Low Energy 4.0 interface for controlling parameters from iOS and Android devices.
Now all our goals are quite specific and realizable.
Visualize Your Concept: PCB Layout for Power Supply Unit
Now that you have a clear idea of your project, it’s time to start designing. Before you start looking for components and drawing diagrams, I suggest developing a clear picture of how your project should function. We need to draw a functional diagram of the device, what is connected with what and how it works.
So far, you do not know what kind of PCB Layout for Power Supply unit is needed or what connectors should be on the board, but you already know how the components will be connected to each other and what additional components will be needed in the project.
This is a good time to consider the aesthetic aspect of your design. Do you want to fit your board into a specific form factor? Do you need to consider ergonomics? Will you be able to open your project in a year and understand what works? These seemingly insignificant details distinguish good design from very good.
This may be the most tedious step in the design process, but it is key to the success of the project. Choosing the right components will determine whether you complete the project successfully or abandon it in despair.
IC manufacturers work hard to create the most functional components at the lowest possible price, but not all companies are equal in this race, especially when it comes to ease of use of components.
Given the millions of different components on the market, it is very difficult to give a complete selection guide, but I can provide some tips to help you select the best components for your application.
1. Check availability. The very last thing you would like to do is delay your project for weeks or even months just because a key component of your project is out of stock with the vendor. Choose components that are in abundance and are available from different distributors.
2. Consider the manufacturing cycle of your components. Sometimes it happens that components are taken out of production and perhaps after a short period of time you will have to make changes to the project, however, if your device is in a single copy, and then this does not play a tangible role.
3. Use filters by component. Many online stores provide very functional filters on the site by component parameters, as well as by cost and availability, use them, select components with the optimal parameters for you, and then filter them by cost.
4. Remember the minimum amount. Many components are sold only in minimum acceptable quantities, for example, starting from 1000 pieces.
5. Choose the right enclosure. Pay attention when choosing components for the case in which it is produced, you should not buy a component that you cannot then solder.
6. Examine the component. Before purchasing, be sure to study the documentation for the component so that in the future there will be no problems with its use in the project.
After all the components are selected, you can order them. Personally, I like to order from online stores like mouser.com or digikey.com. This, of course, is purely my preference. If you know other current suppliers, you can write about them in the comments.
Sketch Your Connections for PCB Layout for Power Supply Unit
The final stage before starting to work with the software is to transfer some of the key points of the project to paper. The most suitable option for PCB Layout for Power Supply unit is to paint each block separately on different pages of the notebook. You can also make all the necessary notes, what is how it works and what this or that pin is responsible for.
Also enter additional information that will be needed in the design process, for example, it can be tedious to look for the addresses of the I2C microcircuit in the datasheet every time, enter them in a notebook.
After you have finished all the entries, you can proceed to the design process directly on the printed circuit board.
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