• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.1-9
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• 2010

An LED driving and control circuit has been developed. The LED driver has a new PWM circuit for current control of LED columns with dimming, current and thermal control, and communication functions. The PWM circuit is composed of two ring oscillator and one counter which can be constructed using basic digital logic components. In addition, it has the functions of remote control mode such as ON, OFF, emergency and power saving modes by the serial communication. The PWM generator and control circuit have been designed and fabricated 0.35[${\mu}m$] Magnachip/Hynix digital IC fabrication process. The LED driving and control board using the developed chip is fabricated and tested successfully.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.3 s.303
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• pp.63-70
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• 2005

The electrodeless lamps using the induction discharge have a long lifetime and a high tolerance for the variable output conditions of a ballast since they don't need the electrodes. This paper proposed two novel dimming algorithms for the Electrodeless lamps and described the resonant inverter adopted the proposed methods. The proposed dimming algorithms are based on the conventional burst dimming method which is normally adopted for LCD back-lights. One of the proposed algorithms is a improved burst dimming method, which controls the illumination by duty ratio of $5\%$ and its control circuit is formed by simple digital logics. The other algorithm is a burst PWM average duty ratio control method, which controls the illumination by duty ratio of $1\%$ and its control circuit is formed by more complex digital logics than the first method. To verify the validity of the proposed dimming methods, a prototype experimental setup for 100W Electrodeless lamps is carried out and its results are presented in this paper.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.200-204
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• 2001

The high efficiency and high power inverter for driving LCD backlight was designed and fabricated. The operating frequency was variable and dimming capability was also included. High dimming ratio could be achieved by PWM dimming. The optimum driving condition for LCD backlight could be obtained by using the excited type inverter.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.548-549
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• 2010

LED의 조도제어 방식은 타 방식에 비해 비교적 광색의 변화가 작고, 선형적인 조도제어가 가능한 PWM 방식을 사용한다. 본 논문은 LED를 PWM 방식으로 조도제어 했을 때, PWM 주파수에 의해 변화 하는 LED의 특성변화를 최소화하도록 주파수를 선택하는 방법을 제안하였으며, 이를 실험적으로 검증하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.89-95
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• 2014

An LED lighting which adjusted brightness according to the surround ambient implemented using PWM technology and power devices. To measure the brightness of surround ambient a CdS sensor was used. A control board for the generation of the PWM signal was made using a MCU and duty ratio was controlled according to light intensity of surround ambient of the system. To drive the LED lamps which require high-voltage and high-current power devices were used for switching the DC power supply. Measurement results show that the IGBT is excellent as only lineality but the PowerBJT is more good to consider to efficiency and cost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.843-848
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• 2006

This paper explains the design and fabrication of an inverter for LCD backlight using a multilayer piezoelectric transformer. That inverter is operated by the burst dimming method whose dimming signal is controlled by the duty ratio of rectangular switching signal to a PWM controller. The brightness of CCFL's are investigated according to the various dimming signals, and when those CCFL's are turned on, the temperature distributions on the piezoelectric transformer and circuit components of the inverter are also investigated by a thermo-camera.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.2
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• pp.8-18
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• 2015

This paper proposes a dimming method and a hybrid LED driving circuit suitable for the ultra high definition (UHD) broadcasting. There are major two problems during the dimming control for traditional LED broadcast lightings; one is a flicker that occurred when camera filming to these lightings, and the other is that linear control is impossible for LED luminous intensity under 10% due to LED electrical characteristics. The proposed dimming method and the driving circuit are designed to solve two problems simultaneously. For high level dimming control region from 10 to 100%, the analog control method was applied to the switching regulator constructed by MOSFET operated in the saturation region. For low level dimming control region under 10%, the fast PWM control method with the linear regulator constructed by MOSFET in the ohmic region was used. We verified experimentally that the dimming method is able to control the luminous intensity linearly from 1 to 100% and the flicker disappears on images taken by the charge coupled device (CCD) and the complementary metal oxide semiconductor (CMOS) cameras. Therefore, the proposed method is suitable for the UHD broadcasting.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1025-1025
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• 2015

본 논문에는 Flyback컨버터의 PWM방식과 조명용 LED 구동장치의 디밍에 의한 조명제어를 제안한다. 제안된 LED 구동회로는 Flyback 컨버터를 이용하여 교류 입력 전원을 직류 출력전원으로 변환되는 과정을 이해한다. 포터커플러의 역할과 그 Feedback원리 그리고 PWM방식으로 IC를 직접 제어하여 버스트 디밍을 구현하고 LED의 밝기 밝기 조절 및 불필요한 전력낭비를 예방하는데 목적을 두었다.

• Journal of Power Electronics
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• v.12 no.6
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• pp.886-894
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• 2012

This paper presents a secondary-side, dual-mode feedback LLC resonant controller IC with dynamic PWM dimming for LED backlight units. In order to reduce the cost, master and slave outputs can be generated simultaneously with a single LLC resonant core based on dual-mode feedback topologies. Pulse Frequency Modulation (PFM) and Pulse Width Modulation (PWM) schemes are used for the master stage and slave stage, respectively. In order to guarantee the correct dual feedback operation, Phased-Locked Loop (PLL)-based automatic duty control circuit is proposed in this paper. The chip is fabricated using $0.35{\mu}m$ Bipolar-CMOS-DMOS (BCD) technology, and the die size is $2.5mm{\times}2.5mm$. The frequency of the gate driver (GDA/GDB) in the clock generator ranges from 50 to 425 kHz. The current consumption of the LLC resonant controller IC is 40 mA for a 100 kHz operation frequency using a 15 V supply. The duty ratio of the slave stage can be controlled from 40% to 60% independent of the frequency of the master stage.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.502-506
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• 2012

본 논문은 LED 조명 환경에서 Zigbee를 이용해서 Dimming 제어 모듈을 구성 하였다. 현재 사용되고 있는 LED 제어 모듈는 일반적으로 단일 출력을 사용하여 LED 조명의 일정한 밝기를 고정 출력이 되도록 사용되어지고 있다. 본 논문에서 구성된 무선 통신 모듈은 Zigbee를 이용하여 실내 환경에서 측정된 조도값을 무선으로 전송하도록 조도 센서 모듈을 구성 하였으며, 무선으로 전송된 조도값에 대한 출력을 제어하도록 구성하였다. MCU는 LED Driver IC를 이용하여 PWM 신호에 따라서 LED Driver IC에서 출력 전압을 변화하도록 하여 6단계의 밝기로 LED조명을 Dimming하도록 구성하였으며, 무선조도 센서는 10~15m의 거리에서 안정적으로 동작된다.