ESR

ESR stands for Equivalent Series Resistance and refers to the resistance connected in series with an ideal lossless capacitor. It determines the magnitude of the resistance in series with the capacitor and can significantly enhance the actual performance of the capacitor. Generally, the lower the ESR value (Equivalent Series Resistance), the higher the quality of the capacitor and the better its effectiveness as a filtering device. ESR is a major factor in determining the ripple of switching power supplies.