One, the overall program selection
According to the design of the task, requirements and conditions, the use of a number of power supply circuits with a certain function to form a whole, in order to achieve the performance indicators of the process. The basic steps of this process is: put forward the program, analysis and comparison and make a choice, generally available block diagrams show the basic principles of the program, if necessary, you can draw specific circuits, so it should be noted that:
1, for the main issues related to the circuit of the overall situation, more than a number of different programs, and and in-depth analysis and comparison, to make a reasonable choice. 2, the composition of the block diagram should take into account the possibility of realizing the key, there is no absolute box in the circuit is necessary to design experiments to meet the design requirements.
3, the choice of the box circuit, ah since four to consider digital circuits, but also consider analog circuits, should be based on specific issues, put forward different programs to fully justify, to get the right conclusion.
4, choose the optimal design, the need to analyze and demonstrate the specific design process of continuous improvement and refinement, in order to achieve "reliable performance, reduce costs, reduce power consumption," the purpose, and sometimes there may be some repetition. But should avoid the program on the big repeated, in order to avoid the waste of human and material resources.
Two, power supply circuit design
In the process of determining the unit circuit, first of all, clear requirements for each unit, the formulation of the main unit circuit performance indicators; secondly, we must pay attention to the interactions between the various unit circuits and connectivity, and can not increase the complexity of the circuit; and finally designed the structure of each power supply circuit form, the selection of components and parameter calculations, and so on. Disadvantages of each unit circuit of the steps are: clear requirements, the choice of the circuit and the calculation of parameters, again the process should consider the following two points.
1, you can design your own or directly refer to the unit circuit has been molded, but can not be blindly copied, if necessary, but also to make certain changes.
2, to clarify the relationship between the power supply circuit and the overall circuit, independent unit circuits may sometimes be better from local considerations, but from the General Assembly to consider, but not necessarily reasonable. Therefore, attention should be paid to select the appropriate components from the overall situation, the combination of the best circuit unit.
Three, the choice of components
In a sense, the design of electronic circuits, is to choose the most appropriate components, and not the best combination of them, therefore, how to choose components, is also an important part of the design process. In the selection process of components should be considered in the main issues are:
1, according to the specific requirements of the program selected, what kind of components are needed, each component has those functions and what kind of performance indicators.
2, generally should give priority to the selection of integrated circuits, integrated circuits can simplify the design of a wide range of applications, and make the assembly, commissioning and maintenance of convenient, but also reduce the size of the electronic equipment and reduce costs, improve the reliability of electronic equipment. Integrated circuits should be clear on the following points:
① Familiar with the typical product model of integrated circuits, performance and price, in order to select the appropriate integrated circuit.
② in the double in-line, flat and single in-line three common package should be in order to choose with the assembly, debugging and maintenance principles.
③ The same function of the digital integrated circuits, there may be TTL products, CMOS products, business and ECL products should be selected according to their respective characteristics, performance and design of the circuit requirements of the application, flexibility. Such as CMOS devices with low power consumption, power supply range than the requirements of TTL devices wide.
Four, the calculation of component parameters
In the electronic circuit design process, the need to calculate certain parameters to select components. Specific requirements are: the use of analytical methods, clarify the circuit principle and use a good formula. Calculate the parameters of the components should be noted:
1, the rated current, voltage, frequency and power consumption of the components should be in the permissible range; in the prescribed conditions of normal operation, and can make the circuit to achieve the performance standard requirements, and leave an appropriate margin.
2, the calculation of parameters, for the ambient temperature, grid voltage and other operating conditions should be considered according to the most unfavorable situation.
For the limit parameters of the crystal transistor, such as BVCEO generally meet the power supply voltage of about 1.5 times to consider.
Under the premise of ensuring circuit performance, should minimize the cost, power consumption, volume and reduce the variety of components, etc., and for assembly, commissioning and maintenance to create convenient conditions.