Light emitting diode driving apparatus
View Patent ↗There is provided a light emitting diode driving apparatus, including: a power supplying unit converting input power into driving power according to a control and supplying the converted driving power to a light emitting diode channel; a driving unit controlling current flowing in the light emitting diode channel according to a pulse width modulation (PWM) dimming signal from the outside; and a controlling unit comparing a reference level set by a duty of the PWM dimming signal with a detection voltage level of the light emitting diode channel and controlling a power converting operation of the power supplying unit according to the comparison result.
1. A light emitting diode driving apparatus, comprising:
a power supplying unit converting input power into driving power according to control and supplying the converted driving power to a light emitting diode channel;
a driving unit controlling current flowing in the light emitting diode channel according to a pulse width modulation (PWM) dimming signal from the outside; and
a controlling unit comparing a reference level set by a duty of the PWM dimming signal with a detection voltage level of the light emitting diode channel and controlling a power converting operation of the power supplying unit according to the comparison result,
wherein the controlling unit includes:
a PWM duty sensing unit sensing the duty of the PWM dimming signal;
a reference level changing unit changing the reference level when the duty of the PWM dimming signal sensed by the PWM duty sensing unit is shorter than a preset reference duty;
a comparing unit comparing the reference level from the reference level changing unit with the detection voltage level of the light emitting diode channel; and
a power controlling unit controlling the power converting operation of the power supplying unit according to the comparison result of the comparing unit,
wherein the light emitting diode channel comprises a plurality of light emitting diode channels connected to each other in parallel,
wherein the driving unit includes a plurality of drivers corresponding to the plurality of light emitting diode channels, respectively, and
wherein each of the plurality of drivers includes:
a switch connected between an end of the corresponding light emitting channel and a ground and controlling the current flowing in the light emitting diode channel according to a switching signal; and
a comparator comparing the PWM dimming signal from the outside with voltage obtained by detecting the current flowing in the switch and controlling a switching operation of the switch.
2. The light emitting diode driving apparatus of claim 1 , wherein the controlling unit changes the reference level when the duty of the PWM dimming signal is equal to or shorter than a preset reference duty.
3. The light emitting diode driving apparatus of claim 1 , wherein the controlling unit further includes a selecting unit selecting one of respective detection voltages of the plurality of light emitting diode channels.
4. The light emitting diode driving apparatus of claim 3 , wherein the selecting unit selects a minimum detection voltage among the detection voltages of the plurality of light emitting diode channels.
5. The light emitting diode driving apparatus of claim 1 , wherein the PWM dimming signal has on/off-duties applied when the switch is switched on.
6. The light emitting diode driving apparatus of claim 2 , wherein the controlling unit maintains an existing reference level when the duty of the PWM dimming signal is equal to or longer than the preset reference duty.