Switch manufacturers to talk about the importance of filter capacitors for electronic designers are aware of, but some easily overlooked problems still need to pay attention and careful. In the switching power supply output filter capacitor used, and the frequency filter circuit used in the capacitor is not the same, in the labor frequency circuit for filtering the general electrolytic capacitor, the ripple voltage frequency of only 100 Hz, charge and discharge Time is in the order of milliseconds, in order to obtain a smaller pulse coefficient, the required capacitance of up to hundreds of thousands of micro-law, which is generally low-frequency ordinary aluminum electrolytic capacitor manufacturing, the goal is to improve the capacity of the capacitor, capacitor capacity, loss angle Zhengqie and leakage current is to identify the main parameters of the pros and cons.
Switch manufacturers on electronic equipment, the capacitor is widely used: such as filtering, decoupling, high-frequency compensation, to provide AC feedback, DC blocking, inhibit Miller effect, and so on. AC rectifier through the diode, in order to obtain a lower ripple voltage, need to be filtered through the capacitor before use. In general, large-capacity filter capacitors can provide smoother output current. But the theory and practice can prove that when the capacitance reaches a certain value, even if the increase of the capacitor to optimize the filter effect has no significant effect, should be based on load resistance and output current size to choose the best capacity. Filter circuit is the most widely used aluminum electrolytic capacitors. Now switch manufacturers of electronic equipment commonly used in two types of power supply, series regulator circuit and switching regulator circuit. These two power circuits have different requirements for output filter capacitors.