Many electronic designers are aware of the role of the filter capacitor in the power supply, but the filter capacitor used at the input of the switching power supply is not the same as the filter capacitor selected for the power frequency circuit, and is used as the filter in the power frequency circuit. popular Electrolytic capacitor, the voltage ripple frequency of 100 Hz only the charging and discharging electrical husband millisecond number of stages, the ripple factor is made smaller, the capacity demand of up to hundreds of thousands of microfarads, and therefore low frequency general popular Electrolytic Capacitor manufacturing, the purpose is to improve the capacity of the main capacitor capacitance, loss tangent and leakage current is to determine the secondary parameters of its good or bad.
Switching power supply used in the filter as the input electrolytic capacitor, the frequency of the sawtooth wave voltage up to tens of kilohertz, and even tens of megahertz, its request and the use of low-frequency differences, capacitance is not a secondary goal, trade-off Its advantage is its impedance-frequency characteristic, requiring it to have low impedance in the switching frequency-stabilized power supply's mission band, and at the same time, with respect to the power supply, since the semiconductor device starts up to hundreds of kilohertz Peak noise, but also have excellent filtering effect, ordinary low-frequency ordinary electrolytic capacitor at 10 kHz, its impedance began to appear rational, unable to meet the switching power supply request.
Switching power supply common high-frequency Aluminum Electrolytic Capacitor, which has a four-terminal, positive two pieces of aluminum lead to identify as a positive electrode capacitor, the negative aluminum sheet is also identified as the two ends lead to negative. The current from the regulated power supply flows from one positive terminal of the four-terminal capacitor to the external via the capacitor and from the other positive terminal to the load. The current from the load also flows from one negative terminal of the capacitor to the other negative terminal Negative side.
Because of the superior high frequency characteristic of the four-terminal capacitor, it provides an extremely advantageous means of reducing the fluctuating weight of the input voltage and of suppressing the switching spike noise.
High-frequency Aluminum Electrolytic Capacitors are also multi-core approach, which will divide the aluminum foil shorter short segment, with multiple leads connected in parallel to reduce resistance in the resistance of the composition, while taking low-resistivity data and the use of screws as a lead Terminals to enhance the ability of the capacitor to accept high currents.
The laminated capacitor is also called non-inductive capacitor. The core of common electrolytic capacitor is rolled into a cylindrical shape, and the equivalent series inductance is larger. The structure of the laminated capacitor is similar to that of the original prototype. Is offset, thus reducing the value of the inductor has a more excellent high-frequency characteristics of this common square made of capacitors, easy to fix, but also can properly reduce the volume of the machine.
In addition, there is a four-terminal and laminated four-terminal laminated high-frequency electrolytic capacitors, which combines the strengths of both, better high-frequency characteristics.
