Output impedance

An equivalent circuit that represents the impedance between output terminals, viewed from the output side of a power supply circuit. The larger the output impedance, the more voltage drop occurs at the output terminals, so it is preferable to have a smaller value, similar to the internal resistance of a battery. Therefore, the output impedance is designed to be as small as possible. Since a switching power supply circuit is an LC circuit consisting of a coil and a capacitor, the overall impedance including the output impedance may increase at the resonance frequency or at integer multiples of that frequency.