A cable compensation circuit compensates a voltage drop in a cable coupled between a power supply and a load. The cable compensation circuit includes: a node where a voltage that depends on an input voltage of the power supply during a turn-on period of a power switch of the power supply and depends on an output voltage of the power supply during a turn-off period of the power switch is generated; a sensing RC filter generating a sense voltage that depends on a diode current by filtering the voltage of the node; and an averaging RC filter generating an average voltage by averaging the sense voltage.