ESR

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