Output impedance

An equivalent circuit representing the impedance between the output terminals as seen from the output side of a power supply circuit. The larger the output impedance, the greater the voltage drop at the output terminals, so as with a battery's internal resistance, it is preferable for it to be small. Therefore, the output impedance is designed to be as small as possible. Since a switching power supply circuit is an LC circuit composed of coils and capacitors, at the resonant frequency or its integer multiples, the overall impedance including the output impedance may become large.