LED driving device of overvoltage protection and duty control
First Claim
1. An light emitting diode driving device comprising:
- an LED array comprising a plurality of light emitting diodes electrically connected to each other;
a pulse with 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.
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Accused Products
Abstract
An LED driving device comprises a PWM IC including 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. The LED driving device sets up the comparison voltage inputted to the COMP terminal of the PWM IC to be 0 when an error voltage corresponding to a difference between a both end voltage of an LED array and a predetermined reference voltage is less than a predetermined level.
63 Citations
4 Claims
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1. An light emitting diode driving device comprising:
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an LED array comprising a plurality of light emitting diodes electrically connected to each other; a pulse with 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. - View Dependent Claims (2, 3, 4)
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Specification