Electronic Design - PCB design steps for Ni-MH battery charger?

1. Introduction to PCB design software Protel

With the rapid development of electronic information technology, PCBs (printed circuit boards) for manual design of electronic products can no longer meet the needs of electronic technology development. We must use the computer to complete the PCB design work, it is not only fast, high accuracy, and can greatly reduce the labor intensity of engineering and technical personnel. There are many kinds of software involved, and Protel is one of the more classic ones.

Protel is a circuit-aided design system launched by Altium. It is the first board-level design system that integrates all design tools, including schematic design, PCB design, circuit simulation, PLD design, etc. Its earliest version was the TANGO software package, which later developed into ProtelforDOS version, ProtelforWindows version, Protel98 version, Protel99SE version, ProtelDXP version and Protel2004 version. With the continuous upgrade of the version, its functions are becoming more and more powerful.

Compared with other versions, many new functions of Protel2004 make the operation simpler and more automated, allowing us to easily carry out various complex circuit board designs.

2. Introduction to PCB design concept and process

PCB is the abbreviation of PrintedCircuitBoard in English, translated as printed circuit board, referred to as circuit board or PCB board.

The printed circuit board is made of conductive circuit and component package by printing method. Its main function is to realize the fixed installation of electronic components and electrical connection between pins, so as to realize various specific functions of electrical appliances. Producing correct, reliable and beautiful printed circuit boards is the ultimate goal of circuit board design.

The general process of PCB design includes: pre-production preparation, PCB component pin packaging, new PCB file planning, circuit board planning, component pin packaging and network loading, layout, wiring, DRC design rule checking, etc.

Third, the PCB design steps of Ni-MH battery charger

Ni-MH battery charger is a common electronic product in our lives. The basic steps of designing the printed circuit board (PCB) of this circuit with Protel2004 are as follows.

1. Create a project file

To facilitate the management of various design files and the seamless connection and synchronization between them. In Protel2004, using project files for management, first create a project file, and then create or add various design files under the project file.

2. Create a schematic file and complete the schematic design of the battery charger circuit

3. Create PCB files and plan

There are two ways to create a PCB file in Protel2004: create with the file menu and create with the wizard. It should be noted that the PCB file created with the wizard is not in the project file. After the creation is completed, it must be placed in the project file, otherwise the following The steps cannot be carried out. According to the composition of the charger circuit, the shape of the board is first planned to be rectangular, and the size of the board is determined to be 2400mil*1300mil according to the number of components. The single-layer wiring is designed as a single-sided board.

4. Load component pin package and network and carry out component layout

All components in this circuit adopt the jack package form. Except for the positive polarity package of the battery pack, other components are packaged in the standard package in the Protel2004 component library. We need to set up the package for the positive terminal of the battery pack according to the actual circuit. First, create our own component package library. Create a package as shown in BT1-BT4 in Figure 2, and then set this package as the package of the battery pack.

The component layout can be performed by the method of automatic layout first and then manual adjustment. Note that the transformer is not placed on this board. When layout, pay attention to the arrangement and distribution of components to be reasonable and even, and strive to be neat and beautiful, and meet the process requirements of circuit structure.

5. Set wiring rules and perform wiring

The so-called "wiring" is to use printed wires to complete the wiring relationship of the components in the schematic diagram. After completing the component layout of any circuit board, the next thing to do is to connect the components with wires to make them have electrical characteristics, thereby forming a complete circuit board.

When wiring in Protel2004, wiring rules must be set first to meet electrical requirements such as safety principles. According to the actual requirements of the charger circuit, the safety distance is set to 10mil, the top layer wiring, the normal line width is 10mil, the power line is 20mil, and the ground line is 30mil. The wiring adopts automatic wiring, and the places that do not meet the requirements can be modified manually. When wiring, under the premise of meeting electrical requirements such as safety principles, the wires should be streamlined, as short as possible, with as few turns as possible, and strive to be simple and clear.

In addition, the wiring design should consider whether the assembly is convenient or not. Finally, the board is required to be beautiful and economical, and a good PCB board has beautiful wiring and fine work, which looks like a work of art.

6. DRC design rule check and error elimination

After the circuit board design is completed, in order to ensure that the design work carried out meets the requirements, the computer can automatically complete the inspection work, that is, the DRC design rule inspection. After the check is completed, the system will pop up the Messages information box, according to this information prompt, modify the design until there are no errors. At this point, the PCB design work of the circuit is completed, and the charger PCB file is designed. Finally, the drawings and reports can be printed out, and the corresponding follow-up work such as actual board making can be carried out.

Fourth, use Protel2004 software to design Ni-MH battery charger circuit board summary

Using Protel2004 software for PCB design, the operation is simple and the degree of automation is high. The Ni-MH battery charger PCB design has the commonality of PCB design and also has certain characteristics. To design a perfect charger PCB, a lot of experience is needed. With the development of electronic technology, electronic circuits are becoming more and more complex, requiring designers to continuously improve their design level and design more PCB quality products.