Many electronic designers know the role of filter capacitors in power supplies, but the filter capacitors used at the output of switching power supplies are not the same as those used in power frequency circuits, and the pulsating voltage frequency on them is only 100 Hz. , the charging and discharging time is on the order of milliseconds. In order to obtain a small pulsation coefficient, the required capacitance is as high as hundreds of thousands of microfarads. Therefore, ordinary low-frequency aluminum electrolytic capacitors are generally used. The goal is to increase the capacitance. , loss tangent value and leakage current are the main parameters to identify their pros and cons.