In LED design, there must be ripple in theory and practice. There are five common ways to suppress or reduce it:
Increase inductance and output capacitance filtering
According to the formula of LED driving power, the current fluctuation in inductance is inversely proportional to the value of inductance, and the output ripple is inversely proportional to the value of output capacitance. Therefore, increasing the value of inductance and output capacitance can reduce the ripple.
Output ripple=Imax/(Co×f). It can be seen that increasing the output capacitance can reduce the ripple.
In general practice, for output capacitors, aluminum electrolytic capacitors are used for the purpose of large volumes. However, the electrolytic capacitor is not very effective in suppressing high-frequency noise, and ESR is also relatively large, so a ceramic capacitor will be connected in parallel beside it to make up for the deficiency of the aluminum electrolytic capacitor.
At the same time, when the LED drive power supply works, the input voltage Vin does not change, but the current changes with the switch. In this case, the input power supply does not provide current very well, and usually near the current input (in the case of the BucK type, near the SWITcH), the shunt capacitance provides the current.

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