• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.14-21
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• 2012

This paper study a method of modeling and simulation of LED driver circuit for a design optimization. Simplified LED modeling is introduced and a driver IC, HV9910, is modeled by implementing the major function blocks. Circuit of buck type converter is constructed for simulation. Simulation includes not only the internal function of IC but also the various performance results such as LED array current control and dimming. Experiment results are also shown to prove the verification of its usage. This results show that the simulation approach is valid for a circuit optimization and a reduction of development time.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.243-250
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• 2009

This paper provides an novel two-stage LED driver circuit for LED lighting equipment. The proposed driver circuit reduces voltage stress in LED driver circuit by using multi-level output voltage of PFC flyback converter. The proposed circuit satisfies IEC61000-3-2 class C regulation that is applied to lighting equipment over 25W and uses PWM to control brightness of wide extent. In this paper, the principle of proposed driver circuit is presented. A prototype has been built and tested. The experimental results are presented to show the validity of the proposed circuit.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.85-88
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• 2008

LED를 구동하기 위하여 여러 가지 주변회로를 하나의 IC로 통합한 Driver IC는 최근 LED의 효율의 증가와 더불어 다양한 사용처의 발생으로 인하여 그 종류가 다양해졌다. 본 연구에서는 이러한 다양한 Driver IC들의 특성을 평가하기 위한 방법 및 다양한 Application의 적용을 통한 Driver IC의 성능을 평가하였다. Driver IC의 기능성과 내구성을 판단하기 위한 시험들을 진행하였다. 여러 종류의 LED를 사용하여 Driver IC의 성능을 평가하였다. Driver IC에 원하는 동작을 구현하고자 하는 제어회로 부분도 설계하여 다양한 특성들을 분석할 수 있도록 하였다. 3종류의 응용제품을 구현하여 적용의 사례로 검토하였고 각각의 응용제품의 경우 필요한 기능들에 대한 분석도 실시하였다. 전체적으로 반도체 IC 시험규격에 의한 신뢰성 시험도 일부 실시를 하여 신뢰성에 대한 부분도 평가를 진행하였다. 이를 통하여 Driver IC의 필요요소에 대한 부분들을 결정하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.612-616
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• 2012

This paper presents an active current regulator for LED driver IC. The proposed driver circuit is consists of DC-DC converter for supplying constant DC voltage to LED, active current regulator for compensating channel-to-channel current error from LED strings and feedback circuit for controlling duty ratio of the converter. The proposed active current regulator senses current of LED channels by equalizing both $V_{DS}$ and $V_{GS}$ at LED current control transistor. Because the proposed circuit directly measures the LED channel current without a sensing resistor and regulates all channel with same regulation loop, the power consumption and the current error are much small compared with previous works. The measured maximum efficiency of overall LED driver IC is approximately 94% and current error of LED channel-to-channel is under ${\pm}1.3%$. The proposed LED driver IC is fabricated Dongbu 0.35um BCD process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1275-1282
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• 2012

This paper proposes the 16-channel LED Driver IC for Full color LED display system. The proposed LED driver IC in this paper can draw current independent of temperature and supply voltage in each channel. Current flow in the channel is configurable via an external resistor. LED brightness is adjusted by 12-Bit PWM(Pulse Width Modulation) and 8-Bit DC(Dot Correction). A real-time monitoring of IC temperature ($130^{\circ}C/150^{\circ}C$) and LED status (open/short) is provided by LED driver IC and the user can receive warning and get information on problems. A 16-channel LED driver IC is produced using 0.35 um BCD process and the size is $2.5mm{\times}2.5mm$. In this paper, channel current characteristic and channel current control function were measured in order to verify am embodied 16-channel LED driver IC by producing a single IC test board.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.101-104
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• 2008

This paper is a report of designing for LED lights driver unit. The main purpose of driver designing is high electrical efficient performance and intelligent control LED driver. This LED driver can be used for intelligent light control. This product expects to improve the light control by dimming instead of interlace on/off light control that increases the social cost such as car accidents and etc.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.79-83
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• 2016

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If thhe distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• Journal of Industrial Technology
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• v.31 no.A
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• pp.103-107
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• 2011

In this paper, a method is proposed to improve power factor and the input current THD in LED driver circuit. The researched circuit consists of a valley-fill circuit and boosting inductor and a Buck converter. Valley-fill circuit is a passive PFC and simplified structure, the buck converter is operated with current feedback. The switching frequency is 50KHz in LED driver circuit and LED forward current is constant. A valley-fill type PFC circuit for LED driver(15Watt) has been implemented, and the validity of proposed method is shown by is simulation and experimental result.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.1-7
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• 2020

In recent years, as LED display systems are actively spread, study on effective control methods for an LED driver for driving the systems has been in progress. The most representative among them is the uniform brightness control method for the LED driver channel. In this paper, we propose an LED driver IC for BLU with current compensation and system protection functions to minimize channel luminance deviation. It is designed for current accuracy within ±3% between channels and a channel current of 150 mA. In order to satisfy the design specifications, the channel amplifier offset was canceled out by a chopping operation using a channel-driving PWM signal. Also, a pre-charge function was implemented to minimize the fast operation speed and luminance deviation between channels. LED error (open, short), switch TR short detection, and operating temperature protection circuits were designed to protect the IC and BLU systems. The proposed IC was fabricated using a Magnachip 0.35-um CMOS process and verified using Cadence and Synopsys' Design Tool. The fabricated LED driver IC has current accuracy within ±1.5% between channels and 150-mA channel output characteristics. The error detection circuits were verified by a test board.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.593-600
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• 2010

In this paper, High brightness LED (light-emitting diodes) driver IC (integrated circuit) using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET (metal oxide semiconductor field effect transistor) from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. To confirm the functioning and characteristics of our proposed LED driver IC, we designed a buck converter. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses 1.0 ${\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre (Cadence) simulation.