A light-emitting diode (LED) driver used to power at least one LED with an alternating current (AC) voltage source is provided. The LED driver includes a rectifying unit applying N-fold higher voltage than the voltage from the AC voltage source to the LED. The rectifying unit includes a first charging unit to charge a first voltage, and a second charging unit to charge a second voltage. The first voltage includes the voltage at the AC voltage source during a first half-cycle of one AC voltage cycle, and the second voltage includes the first voltage and the voltage at the AC voltage source during the second half-cycle of the AC voltage cycle. Accordingly, the LED driver may improve light-emitting efficiency and reduce flicker of LEDs.