Output impedance

An equivalent circuit representing the impedance between the output terminals as seen from the output side of a power supply circuit. The greater the output impedance, the more voltage drop occurs at the output terminals, so a lower impedance is desirable, similar to the internal resistance of a battery. Therefore, the output impedance is designed to be as low as possible. Since a switching power supply circuit is an LC circuit composed of coils and capacitors, the overall impedance including the output impedance can become large at the resonant frequency or its harmonics.