The selection of inductance value shall consider not only the noise frequency to be filtered, but also the reaction ability of instantaneous current. If the output terminal of LC has the opportunity to output a large current instantaneously, the inductance value will be too large to hinder the speed of this large current flowing through the inductor, increasing ripple noise. The capacitance value is related to the allowable ripple noise specification value. The smaller the ripple noise value is required, the larger the capacitance value will be. The capacitor ESR/ESL will also have an impact. In addition, if the LC is placed at the output end of the switching regulation power, pay attention to the influence of the pole/zero generated by the LC on the stability of the negative feedback control circuit.
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