PCB Technical - ​Explain what the capacitance of PCB design should be?

The structure and characteristics of the capacitor designed by potential are suitable for the conductor, and the conductor is charged. However, at the same potential, the amount of charge contained in a conductor varies with its own structure. The ability of a conductor to hold charge is called the capacitance of a PCB design. Normally, the charge Q (Coulomb) in a conductor is proportional to its potential V (Volt, relative to the earth), that is, it exists, so C is the capacitance of the conductor PCB design. The capacitance unit of PCB design is Farah(F).

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Insulating medium is inserted between two parallel metal plates, and the wire electrode becomes a capacitor designed by PCB. PCB design The design of the printed circuit board is based on the circuit schematic diagram to achieve the functions required by the circuit designer. The design of the printed circuit board mainly refers to the layout design, and the layout of external connections needs to be considered. The circuit symbol is the capacitance of the polar PCB design and the capacitance of the non-polar PCB design. If the capacitor of the PCB design is charged, the charge will accumulate on the bipolar plate of the capacitor of the PCB design. A capacitor with a capacitance of C designed for PCB is represented by a constant current intensity I. It is assumed that the capacitor of the PCB design is initially uncharged, that is, the initial voltage across the capacitor is equal to zero. We remember the definition of current: the amount of charge passing through the cross-section of the conductor per unit time is called the current intensity, that is to say, it exists because it is in the capacitor of the PCB design.

Therefore, the amount of charge flowing through the cross-section of the conductor per unit time is called the current intensity. Is the current intensity.

is the capacitance of the PCB design and the capacitance C of the PCB design. Under the action of constant current intensity I, the voltage V at both ends increases linearly with time. The higher the voltage across the capacitor of the PCB design, the more charge it contains, and the greater the energy storage. However, the resistance of the insulating medium between the two plates of the capacitor designed by the PCB is limited. If the electric field strength between the two plates is too high, the insulating medium may break down, and the capacitor designed by the PCB will be short-circuited. Therefore, in practical applications, it is necessary to coordinate the voltage and resistance of the capacitors designed by the PCB. Conclusion: The capacitor designed by PCB has the function of containing electric charge in the circuit, that is, the function of energy storage. The capacitor designed by PCB has a long energy storage time and cannot change the voltage at both ends of the capacitor designed by PCB. The larger the capacitance of the PCB design, the more energy can be stored. The capacitance and voltage resistance of PCB design are the two most important parameters in PCB design. 2. The RC charging and discharging circuit circuit is represented by the RC charging and discharging circuit. Assuming that the initial voltage across the capacitor of the PCB design is zero and the switch K is connected to one end, the power supply charges the capacitor of the PCB design through the resistor R. The charging current of the capacitor of the PCB design is the maximum E/R. If you continue to charge with this current, The rising curve of VC is a straight line. However, due to the charging current in the entire charging process, with the increase of VC, the charging current intensity IC gradually decreases, and the amplitude of VC gradually increases until it rises to the power supply voltage E, and the charging current is zero at the same time. This forms the actual VC rising curve. Vc rises exponentially, and its change over time t is expressed as

Here is the time constant.

It can be seen that the larger the series resistance R, the smaller the charging current, and the longer the charging time; the larger the capacitance C of the PCB design, the more power required (that is, the more energy stored), and the longer the charging time.

When the capacitor designed by the PCB board is overcharged, VC is equal to E. When the switch K is turned on, the discharge current of the capacitor designed by the PCB after R is discharged gradually decreases, and the discharge current gradually decreases. The optimized layout of the internal electronic components of the PCB design company, the optimized layout of metal connections and through holes, electromagnetic protection, heat dissipation and other factors, excellent layout design can save production costs and achieve good circuit performance and heat dissipation performance.