Selection and Conversion of Filter Capacitor in 5V Stabilized Power Supply
The main function of the filter capacitor is to eliminate noise and ripple and stabilize the output voltage
There are two types of 5V regulated power supplies, one is a linear regulated power supply with a lower operating frequency, and the other is a switching power supply with a higher operating frequency. Different power supplies need to choose different filter capacitors.
5V linear regulated power supply
In the linear regulated power supply with relatively low operating frequency, there are relatively few noises and ripples. The function of the filter capacitor is mainly to stabilize the output voltage. The larger the capacity of the filter capacitor, the better the effect. Capacitors can replenish energy in time to prevent the voltage from being pulled down instantaneously. The 2200uf capacitor is also considered a large capacity capacitor. If the output current is large, consider increasing the capacitance of the filter capacitor.
5V switching power supply
The operating frequency of the switching power supply is relatively high, generally tens of KHz, and there are relatively many noises and ripples. It is necessary to consider the capacitance impedance and frequency characteristics. The larger the filter capacitance is, the better. Because the capacitance value will drop sharply after the frequency of the power supply increases, so we need to consider ESR (equivalent series impedance) when selecting the filter capacitor. Try to use a filter capacitor with a small ESR value. Capacitors need to have a lower equivalent impedance in the operating frequency to have a good filtering effect
When selecting a capacitor, you need to consider the operating frequency, output voltage, output current, and capacitor value of the switching power supply. You can refer to the calculation formula of the predecessors: C>0.289/{f×(U/I)×ACv}, where ACv is the ripple coefficient , the unit is %.
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