Patent ID: 7423389

Claim:
A light emitting diode driving device comprising: an LED array comprising a plurality of light emitting diodes electrically connected to each other; a pulse width modulation IC comprising an RT/CT terminal operated by a power voltage and generating and outputting a sawtooth wave voltage of a predetermined frequency, a COMP terminal to which a comparison voltage compared with the sawtooth wave voltage is inputted, and an output terminal generating and outputting a pulse signal turned off in a section in which a level of the sawtooth wave voltage is higher than a level of the comparison voltage and turned on in a section in which the level of the sawtooth voltage is lower than the level of the comparison voltage; a switching portion switching and providing an inputted DC voltage to the light emitting diode array as a driving voltage, according to the pulse signal outputted from the pulse with modulation IC; a voltage detector generating a detection voltage corresponding to a both end voltage of the light emitting diode array; a voltage comparator comparing the detection voltage with a predetermined reference voltage and outputting a first error voltage corresponding to a difference between the detection voltage and the reference voltage; and a comparison voltage setting portion setting up the comparison voltage inputted to the COMP terminal of the pulse with modulation IC to be 0V when the error voltage is less than a predetermined level.