In the study of PCB reverse technology, the reverse schematic is a PCB circuit diagram based on the PCB file diagram reverse or directly depicted from the product object, which aims to illustrate the circuit board principle and operation. And, this circuit diagram is also used to analyze the functional characteristics of the product itself. In the forward design, the development of the product is generally done with the schematic design and then the PCB design based on the schematic.
Whether it is used to analyze the circuit board principles and product operating characteristics in reverse research, or reused as the basis and foundation for PCB design in forward design, PCB schematics have a special role. So, according to the file diagram or physical, how to reverse the PCB schematic, the reverse process has to pay attention to those details?
First, a reasonable division of functional areas
In the reverse design of a PCB board intact schematic, a reasonable division of functional areas can help engineers reduce some unnecessary trouble and improve the efficiency of drawing. Generally speaking, a PCB board with the same function of the components will be arranged centrally, to functionally divide the area can have a convenient and accurate basis for the reverse schematic diagram.
However, the division of this functional area is not arbitrary. It requires engineers to have a certain understanding of electronic circuit-related knowledge. First, find out the core components in a functional unit, and then according to the alignment connection can be followed to find out the other components of the same functional unit, forming a functional partition. The formation of functional partitions is the basis for schematic drawing. In addition, in this process, do not forget to cleverly use the component serial number on the board, they can help you faster functional partitioning.
Second, find the right reference parts
This benchmark can also be said to be the main component PCB network city at the beginning of the schematic drawing with the help of the benchmark, after determining the benchmark, according to the pins of these benchmark to draw, to a greater extent to ensure the accuracy of the schematic.
For engineers, the determination of the benchmark is not a very complicated matter, in general, you can choose to play a major role in the circuit components as the benchmark, they are generally larger, more pins, convenient for drawing, such as integrated circuits, transformers, transistors, etc., can be used as a suitable benchmark.
Third, the correct distinction between lines, reasonable drawing wiring
For the ground, power, signal line distinction, the same need for engineers to have the relevant power knowledge, circuit connection knowledge, PCB wiring knowledge and so on. The distinction of these lines can be analyzed in terms of component connection, line copper foil width, and the characteristics of the electronic product itself.
In wiring drawing, in order to avoid line crossings and interpolations, ground symbols can be used extensively for ground lines, and various lines can be used in different colors to ensure that they are clearly identifiable, and special signs can also be used for various components, and even unit circuits can be drawn separately and then combined at the end.
Fourth, master the basic framework, drawing on similar schematics
For some basic electronic circuit framework composition and schematic drawing, engineers need to master, not only to be able to some simple, classic unit circuit of the basic composition of the form of direct drawing, but also to form the overall framework of the electronic circuit. On the other hand, do not ignore that the same type of electronic products in the schematic diagram has a certain similarity PCB network city, engineers can accumulate experience based on the full reference to similar circuit diagrams to carry out the backpropagation of new product schematic diagrams.
Five, check and optimize
After the completion of the schematic drawing, but also after testing and verification links to say that the reverse design of the PCB schematic end. The nominal values of components sensitive to PCB distribution parameters need to be checked and optimized, according to the PCB file diagram, the schematic diagram for comparative analysis and verification to ensure that the schematic diagram and the file diagram are identical.
If the schematic layout is found to be inconsistent with the requirements in the check, schematic adjustments will be made until it is completely reasonable and standardized, accurate and clear.