• JSTS:Journal of Semiconductor Technology and Science
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• 제15권3호
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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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%

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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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.