Led lighting device

A LED lighting device comprises:

• an LED unit comprising a first LED string made by connecting a plurality of first LEDs emitting light at a first color temperature in series and a second LED string made by connecting a plurality of second LEDs emitting light at a second color temperature different from the first color temperature in series, wherein the first LED string and the second LED string are connected in inverse-parallel;
• a converter unit configured to supply a DC voltage to the first LEDs and the second LEDs;
• a signal control unit configured to output a first control signal for emitting light of the first LEDs and a second control signal for emitting light of the second LEDs in consideration of the difference in operating voltage according to the color temperature of the first LEDs and the color temperature of the second LEDs, wherein the signal control unit configured to output the first control signal and the second control signal as PWM (Pulse Width Modulation) signals;
• and
• a LED driving unit configured to provide the DC voltage supplied from the converter unit to the first LEDs or the second LEDs by turning on or off a plurality of switches according to the first control signal or the second control signal.