In the research of PCB reverse technology, reverse deduction schematic diagram refers to reverse deduction based on PCB file diagram or directly depicts PCB circuit diagram according to the actual product, aiming to explain the principle and working condition of PCB board. Moreover, the deduced circuit diagram is also used to analyze the functional characteristics of the product itself. In the forward design, the research and development of general products should first carry out the schematic diagram design, and then carry out the PCB design according to the schematic diagram.
Whether it is used to analyze circuit board principles and product operating characteristics in reverse research, or reused as the basis and basis for PCB design in forward design, PCB schematic diagrams have a special role. So, how to deduce the PCB schematic diagram according to the file diagram or the real object? What details should be paid attention to in the reverse push process?
1. Reasonable division of functional areas
When performing the reverse design of a schematic diagram of a complete PCB circuit board, a reasonable division of functional areas can help engineers reduce some unnecessary troubles and improve the efficiency of drawing. Generally speaking, components with the same function on a PCB board will be arranged in a centralized manner, and dividing the area by function can provide a convenient and accurate basis for reverse derivation of the schematic diagram.
However, this division of functional areas is not arbitrary. It requires engineers to have a certain understanding of electronic circuit related knowledge. First, find out the core components in a certain functional unit, and then find out other components of the same functional unit according to the wiring connection to form a functional partition. The formation of functional partitions is the basis of schematic diagram drawing. In addition, in this process, don't forget to make good use of the component numbers on the circuit board, which can help you perform functional partitioning faster.
2. Find the reference parts
This reference part can also be said to be the main component used at the beginning of the drawing of the schematic diagram. After the reference part is determined, drawing according to the pins of these reference parts can ensure the accuracy of the schematic diagram to a greater extent.
For engineers, the determination of reference parts is not a very complicated matter. In general, you can choose the components that play a major role in the circuit as reference components. They are generally larger in size and have more pins, which are convenient for drawing, such as integrated circuits, transformers, transistors, etc., can be used as suitable reference components. Benchmarks.
3. Correctly distinguish lines and draw wiring reasonably
For the distinction between ground wires, power wires, and signal wires, engineers also need to have relevant power supply knowledge, circuit connection knowledge, PCB layout knowledge, and so on. The distinction of these lines can be analyzed from the aspects of the connection of components, the width of the copper foil of the line, and the characteristics of the electronic product itself.
In wiring drawing, in order to avoid crossing and crossing lines, a large number of grounding symbols can be used for ground lines, and different lines of different colors can be used for various lines to ensure clarity. Special signs can also be used for various active devices, and even Unit circuits can be drawn separately and combined at the end.
4. Master the basic framework and learn from similar schematic diagrams
Engineers need to be proficient in the frame composition and schematic drawing of some basic electronic circuits, not only to be able to directly draw the basic composition forms of some simple and classic unit circuits, but also to be able to form the overall framework of electronic circuits.
On the other hand, don't ignore that the same type of electronic products have certain similarities in schematic diagrams. Engineers can draw on similar circuit diagrams to invert new product schematic diagrams based on accumulated experience.
5. Check and optimize
After the schematic drawing is completed, the reverse design of the PCB schematic diagram can only be said to be completed after testing and checking. The nominal value of components sensitive to PCB distribution parameters needs to be checked and optimized. According to the PCB file diagram, the schematic diagram is compared, analyzed and checked to ensure that the schematic diagram is completely consistent with the document diagram.
If the layout of the schematic diagram is found to be inconsistent with the requirements during the check, the schematic diagram needs to be adjusted until the required rationality, standardization, accuracy and clarity are achieved.