• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.560-561
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• 2012

LED는 전기적 규격 측면에서 특정 전압을 넘기지 않게 하기 위해서는 다채널로 분할해야 하는데, SMPS가 어떠한 채널에 맞춰 정전압 정전류 제어를 할 지 알 수 없다. 이를 해결하기위해 LED 구동 회로에 적용되는 LED String 최대전압을 검출하고 검출된 전압에 의해서 컨트롤 하게 되면, LED String의 전압이 각 채널별로 차이가 발생할 때 전압 강하를 최소화 할 수 있다. 또한 최대 전압을 감지하여 LED 전압을 변화하면 효율을 극대화 할 수 있다. 회로 구현을 통해서 이상이 구현 가능한지 타당성을 검증하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.938-941
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• 2012

LED is divided to multichannel in order not to exceed a certain voltage in aspects of electric standard. However, it's not possible to know in accordance with what channel SMPS controls the constant voltage and current. In order to solve this problem, it needs to detect the maximum LED String voltage which is applied to LED control circuit, and it is possible to minimize the voltage drop when a difference of LED string voltage occurs by each channel if LED is controlled by the maximum LED string voltage detected. In addition, it is also possible to maximize the efficiency of LED if change LED voltage by detecting the maximum voltage. Feasibility of this claim was verified through implementation of the circuit.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.3
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• pp.390-396
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• 2015

This paper proposes a method to reduce flicker when running an AC-power direct-drive type multiple string LED driver IC. The proposed method greatly decreases flicker using one capacitor and P-type MOSFET transistor (PMOS). The flicker index (FI) was reduced by over 40% through experiments, and less than half of the conventional external components are used in the passive valley fill circuit, which gives an advantage in the cost and utilization in the design of LED lighting modules. The 0.35 um 700 V BCD process was used to manufacture this LED driver.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1513-1517
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• 2012

As demands for green industry increase, this paper proposes a power control technique that can substitute pre -existing CCFL(Cold Cathode Fluorescent Lamp) and optimize power consumption of LED BLU. This technique is designing LED driver circuit that make a DC-DC output voltage(VLED) to have a linear control function for a supply voltage of LED string. The proposed LED driver have an advantage that can increase or decrease a DC-DC output voltage compared with conventional LED driver. The designed LED driver circuit was designed using 0.35um CMOS technology. And its operation was verified through simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.253-256
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• 2011

LEDs have small size, long lifespan, high reliability, low power consumption and high color efficiency. Using such a characteristics, LED Back Light Unit has been studying actively. This paper proposes LED driver to minimize power consumption due to LED forward voltage($V_F$) difference and temperature rising. Compared to conventional LED driver, the proposed driver have excellent stability, brief structure and linear output voltage of DC-DC boost converter. Proposed LED Driver circuit was designed using 0.35um CMOS technology. And its operation was verified through simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.117-122
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• 2013

The distributed power conversion LED driver circuit using parasitic inductance is proposed in this paper. while the conventional LED driver circuit is composed of the large size devices and heatsinks, the proposed circuit can be realized with the small sized no heatsink based. since the processing power can be effectively distributed. Also by using the wire parasitic inductance of the LED string, the proposed circuit can be implemented without external magnetic device. As a result, the proposed circuit which features the small size and volume con be realized even without LED driver module(LDM) board. since, all the device can be attached to the existing LED array Module(LAM) board. Therefore, it features that cost savings and volume reduction of circuit. To confirm the validity of the proposed circuit, theoretical analysis and experimental results from a distributed power conversion LED driver circuit prototype are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.9-15
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• 2021

In multi-string light-emitting diode (LED) driver system, current balancing is crucial because the brightness of LED is directly related to its forward current. This paper presents a novel LED current balancing topology using current-fed Z-source converter. With the proposed structure, currents flowing through two LED strings are automatically balanced owing to the charge-balance condition on capacitors. Operation of the proposed converter is simple and the proposed converter uses only one active switch and one diode. Moreover, low-side gate driving can be used to operate the active switch. To verify the operation of the proposed LED current balancing converter, a prototype is built and tested with different numbers of LEDs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.235-240
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• 2010

In order to substitute incandescent lamps, a power supply device for 7W class LED lamps which are environmentally friendly and energy saving is designed LED lamps consist of a multitude of chip LED connected in parallel and series. 11ms it is necessary to supply LED lamps with DC voltage and current. However, when LED lamps are in use, they are connected directly to AC 220V. This is why we need to have AC/DC, DC/DC power converters including a control system of voltage and current. For this, a transformerless and simple LED lamp driver is designed 조ich can control the current and output voltage for LED string of LED lamp.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.333-334
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• 2017

본 논문에서는 스위칭 타입의 AC LED 구동회로를 제안한다. 제안한 회로는 inverted buck 토폴로지를 기반으로 LED string이 직렬로 연결된 구조를 가진다. 제안한 구동회로는 복수개의 bypass 스위치를 통해 입력 전압 레벨에 따라 LED 전압을 조절해가며 인덕터에 유기되는 전압을 조절함으로써 전류 리플 및 스위칭 주파수를 줄이도록 하였다. 이는 기존 선형 타입의 구동회로에 비해 효율을 향상시키면서 넓은 전압 영역에서 동작시킬 수 있다는 특징이 있다. 기본 구조와 동작원리를 제시하고, $110V_{rms}$ 입력의 LED 구동회로 설계와 모의실험을 통해 타당성을 검증한다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.179-180
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• 2011

This paper focuses on the Current-Voltage concurrent control method devoted to the multiple LED (light-emitting diode) string driver. Isolated DC to DC converter with cascaded chopping switch is proposed for smart lighting system such as light with sensor or back light unit of display, which need to control the current of parallel connected multiple LED stings and regulate DC voltage for micro controller for brightness control. The proposed circuit regulates the current of parallel connected multiple LED strings and additional DC voltage output simultaneously. To verify the performance, experimental results are presented based on the prototype board. 5V, 1A voltage mode electric load and two LED strings with different forward voltages are used for output loads. 23W output power is achieved and measured efficiency is in the range of 85%-87%