A power supply, a power control method and a display apparatus having the same, for controlling a standby mode, are provided. The power supply of an electronic apparatus includes: a rectifier configured to rectify a current of alternating current (AC) power input as input power, into a direct current (DC); a power factor correction (PFC) circuit configured to correct a power factor of a DC voltage converted by the rectifier; a switching circuit configured to convert the DC voltage output by the PFC circuit into a predetermined operating voltage and a standby voltage and supply the operating voltage and the standby voltage to the electronic apparatus; and an output controller configured to control the PFC circuit and the switching circuit to convert the DC voltage into the predetermined operating voltage and standby voltage by the switching circuit and supply the operating voltage and the standby voltage to the electronic apparatus.