Seoul Semiconductor Co., Ltd.

Keith Hopwood

Sang Wook Han

Sung Ho Jin

Hyung Jin Lee

Hye Man Jung

In Seok Baek

An LED lighting apparatus capable of color temperature control includes a color temperature controller to receive a color temperature selection signal and output first and second control signals; a LED driver connected a plurality of LED groups; and a LED selection circuit including a first switch connected to a first node to which a rectified voltage is applied and receiving the first control signal, a first LED group selectively connected to the first node by the first switch, a second LED group connected in scales with the first LED group, a third LED group selectively connected to the first node by the first switch, a fourth LED group connected in series with the third LED group, and a second switch for selectively connecting the output terminal of the second LED group or the fourth LED group to the LED driver by receiving the second control signal.

LED lighting apparatus capable of color temperature control

An LED lighting apparatus including a rectifier to rectify AC voltages having different magnitudes and generate driving voltages corresponding to rectified voltages, a buck converter connected to an output terminal of the rectifier and generate an LED driving current corresponding to the driving voltages, a variable reference voltage comparator to receive the driving voltages, and generate variable reference voltages that fluctuate in correspondence to magnitudes of the output driving voltages, compare the driving voltages and the variable reference voltages, and output signals for controlling an operation of the buck converter, an LED including at least one LED group and driven by the LED driving current generated by the buck converter, and a controller including a converter controller to control the operation of the buck converter and a constant current controller to constant current-control the LED driving current applied to the at least one LED group.

LED lighting apparatus and LED driving circuit thereof

An LED lighting apparatus capable of color temperature control includes a color temperature controller to receive a color temperature selection signal and output first and second control signals; a LED driver connected a plurality of LED groups; and a LED selection circuit including a first switch connected to a first node to which a rectified voltage is applied and receiving the first control signal, a first LED group selectively connected to the first node by the first switch, a second LED group connected in series with the first LED group, a third LED group selectively connected to the first node by the first switch, a fourth LED group connected in series with the third LED group, and a second switch for selectively connecting the output terminal of the second LED group or the fourth LED group to the LED driver by receiving the second control signal.

A lighting apparatus including an LED circuit including a plurality of serially connected stages configured to receive a modulated rectified voltage, each of the stages including a first path including a first resistor and a first LED connected in series, and a second path connected to the first path in parallel and including a second LED configured to emit light having a color temperature different from that emitted from the first LED, and a driving current controller configured to adjust an intensity of light output from the LED circuit by adjusting currents applied to driving nodes connected to the stages, depending on a dimming signal associated with a dimming level of the rectified voltage, in which a threshold voltage of the first LED is lower than that of the second LED.

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Ansan-si, South Korea

Keith Hopwood