In the research of PCB reverse technology, reverse push schematic diagram refers to the reverse of PCB file diagram or PCB circuit diagram drawn directly according to the physical object of the product, in order to explain the principle and the working state of the circuit board. In addition, the circuit diagram is also used to analyze the functional characteristics of the product itself. In forward design, general product development must first carry out schematic design, and then carry out PCB design according to schematic design.
The PCB schematic has a special role, whether it is used to analyze circuit board principles and product operation characteristics in reverse study, or as the basis and foundation of PCB design in forward design. So, how to reverse the PCB schematic, and what details should the reverse process pay attention to, based on documentation or real things?
1. Reasonably divide functional areas
When the schematic diagram of PCB board is reversely designed, the reasonable division of functional areas can help engineers reduce unnecessary trouble and improve efficiency of drawing.In general, components with the same function on the PCB will be arranged in a centralized manner, and the functional partition area can have a convenient and accurate basis when the schematic is reversed. 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 the functional unit, and then according to the trace connection, find out other components of the same functional unit, and form a functional partition. The formation of functional partitions is the basis of the schematic. Also, don’t forget to use component serial numbers on the board during the process, which can help you partition functionality faster.
2. Find benchmarks
This reference can also be said to be the main part of the PCB copy board at the beginning of schematic drawing. After the reference parts are identified, drawing according to the pins of these reference parts can ensure the accuracy of the schematic diagram to a greater extent. The determination of the reference part is not a very complicated problem for engineers. Usually, the component that plays a major role in the circuit can be selected as the reference component. They are usually large and have many pins, which are easy to stretch. Such as integrated circuits, transformers, transistors, etc., can serve as a suitable reference.
3, correctly distinguish lines, reasonable line
In order to distinguish ground, power and signal lines, engineers also need to have knowledge of power supply, circuit connection, PCB wiring and so on. The differences between these wires can be analyzed from the connections of the components, the width of the copper foil in the circuit, and the characteristics of the electronics themselves. In wiring diagrams, ground wires can be used in a large number of ground symbols to avoid crossing and scattering lines. Lines can be clearly distinguished by using different lines in different colors, and special symbols can be used for various components, and even unit circuits can be drawn individually and eventually combined.
4. Master the basic framework and refer to similar schematic diagrams
For some basic electronic circuit frame and principle drawing methods, engineers need to master, not only to directly draw the basic composition of some simple and classic unit circuit, but also constitute the overall framework of electronic circuit. On the other hand, do not ignore similar electronic products in PCB copy board schematic diagram has certain similarity. Engineers can make full use of similar schematics to perform the reverse of new product schematics based on experience.
5. Check and optimize
After completing the schematic, you must reverse design the PCB schematic by testing and checking the links. The nominal values of components sensitive to PCB distribution parameters need to be checked and optimized. According to the PCB file drawing, the schematic drawing is compared and analyzed to ensure that the schematic drawing is exactly the same as the file drawing. If the schematic layout is found not to meet the requirements during the inspection, the schematic will be adjusted until it is completely reasonable, standardized, accurate and clear.