PCB Technical - PCB design scheme of battery charger circuit

Protel is a circuit aided design system introduced by Altium Company. It is a board-level design system that integrates all design tools into one, including schematic design, PCB design, circuit simulation, PLD design and so on.

Introduction to 1 Protel Software

With the rapid development of electronic information technology, the PCB (printed circuit board) of manually designed electronic products can no longer meet the needs of the development of electronic technology. We must use computer to complete the design of PCB. It is not only fast and accurate, but also can greatly reduce the labor intensity of engineering and technical personnel. There are many kinds of software involved, Protel is one of the more classical.

Protel is a circuit aided design system introduced by Altium Company. It is a board-level design system that integrates all design tools into one, including schematic design, PCB design, circuit simulation, PLD design and so on. Its earlier version was the TANGO software package, which later developed into Protel for DOS, Protel for Windows, Protel 98, Protel 99 SE, Protel DXP, and Protel 2004. As versions continue to upgrade, they become more and more powerful.

Compared with other versions, Protel 2004 adds many new features that make the operation simpler and more automated, allowing us to easily perform a variety of complex circuit board designs.

2.PCB Design

PCB is the abbreviation of Printed Circuit Board in English. It is translated into printed circuit board, or PCB board for short. Printed circuit boards (PCBs) are printed methods to make conductive circuits and component packages. Their main functions are to achieve the fixed installation of electronic components and the electrical connection between pins, thus achieving various specific functions of electrical appliances. To make a correct, reliable and beautiful printed circuit board is the ultimate goal of the circuit board design.

The general process of PCB design includes preparation, pin packaging of PCB components, new PCB files, planned circuit board, pin packaging of loaded components and network, layout, wiring, DRC design rules check, etc.

3.PCB Design of 3 Ni-MH Battery Charger

Ni-MH battery charger is a common electronic product in our life. The basic steps to design the printed circuit board (PCB) of the circuit with the help of Protel 2004 are as follows.

3.1 Create project files

To facilitate the management of design files and seamless connection and synchronization between them. In Protel 2004, project files are used for management. First, create a project file, then create or add new design files under the project file.

3.2 Create schematic file and complete schematic design of battery charger circuit

3.3 Create and plan PCB files

There are two ways to create a PCB file in Protel 2004: using the File menu to create and using the wizard to create. Note that the PCB file created by the wizard is not in the project file, it must be placed in the project file after the creation is completed, otherwise the next steps cannot be carried out. According to the composition of the charger circuit, first plan the shape of the board to be rectangular, and determine the size of the board to be 2400 mil according to the number of components * 1300mil, single layer wiring is designed as single panel.

3.4 Load component pin packaging and network and component layout

All the components in this circuit are packaged in the form of sockets. In addition to the positive polarity packaging of the battery pack, all other components are packed using the standard packaging in the Protel 2004 Component Library. We need to set up the packaging for the positive polarity end of the battery pack according to the actual circuit. First, we create our own component packaging library, create the packaging shown in BT1-BT4 in Figure 2 in the library, and then set this packaging as the battery pack packaging.

Component layouts can be automated and then manually adjusted. Note that the transformer is not placed on this board. When laying out, attention should be paid to the reasonable and even arrangement and distribution of components, so as to make them neat, beautiful and conform to the technical requirements of circuit structure.

3.5 Set up wiring rules for wiring

The so-called wiring refers to the use of printed guidance lines to complete the connection of components in the schematic diagram. After any printed circuit board has finished the layout of the components, the next thing to do is to connect the components with wires to make them have electrical characteristics so as to form a complete circuit board.

When wiring in Protel 2004, first set up wiring rules to meet electrical requirements such as safety principles. According to the actual requirements of the charger circuit, the safe spacing is set at 10mil, the top layer wiring, the normal widths are 10mil, the power cord is 20mil, and the ground wire is 30mil. The wiring uses automatic wiring, which can be manually modified where it does not meet the requirements. Under the precondition of meeting the electrical requirements such as safety principles, the wires should be simplified, as short as possible, with as few turns as possible, so as to make the wires simple and clear.

In addition, the routing design should consider whether the assembly is convenient, etc. It also requires beautiful, economical board, good PCB board wiring, fine work, looks like a work of art.

3.6 DRC design rule checks and error removal.

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, DRC design rules inspection. When the check is complete, a Messages message box pops up, prompting you to modify the design until there are no errors. The PCB design of the circuit is completed here, and the designed charger PCB file is shown in Figure 2 above. You can print out drawings and reports for follow-up work such as actual board making.

PCB design using Protel 2004 software is simple to operate and highly automated. The design of Ni-MH battery charger PCB has the common characteristics of PCB design as well as certain characteristics. To design a perfect charger PCB requires a lot of experience.