• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.476-484
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• 2010

Recently, as the piezoelectric transformer technology develops, piezoelectric transformer may become a variable alternative to magnetic transformers in various applications. Because it was have to favorable characteristics such as electromagnetic-noise free, compact size, higher efficiency, and superior power density, linkage flux, noiseless, etc. its resonance frequency was used to output waveform of a sine wave. In this paper, the switching mode power supply of about 87.2[KHz] is driven by the multilayer thickness vibration mode piezoelectric transformer and the DC to DC converter drive circuit using an electrical equivalent circuit is proposed. Also, it was possible to drive power source device of the high-luminance LED by propose circuits.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.303-308
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• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive this LED lighting, various types of power converters have been applied. Also, power factor correction (PFC) techniques play an important role in the power supply technology. In this paper, design and control of a DCM interleaved boost PFC converter is discussed. The proposed converter can reduce current ripples at input and output side by cancelling an each phase of inductor currents. Since the IC does not require the auxiliary winding of inductor for current detection, simple PFC circuit is achieved. Therefore, it contributes to increase efficiency and downsize the whole system volume, cost. Also, the performance of the proposed system is demonstrated through experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.87-93
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• 2012

In this paper, we propose an analog-to-digital converter to set the address of a I2C slave chip. The proposed scheme converts a fixed voltage between 0 and VDD to the digital value which can be used as the address of the slave chip. The rising time and the falling time are measured with digital counter in a serially connected RC circuit, while the circuit is being charged and discharged with the voltage to be measured. The ratio of the two measured values is used to get the corresponding digital value. This scheme gives a strong point which is to be implementable all the parts except comparator using digital logic. Although the method utilizes RC circuit, it has no relation with the RC value if the quantization error is disregarded. Experimental result shows that the proposed scheme gives 32-level resolution thus it can be used to configure the address of the I2C slave chip.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.151-155
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• 2016

In this paper, we present the LED dimming control system by using ADPCM (Adaptive Differential Pulse Code Modulation). This ADPCM apparatus accurately controls the LED current with high resolution reducing the RFI (radio frequency interference) due to the spreading out of the harmonics of current of pulses. Additionally, this makes it easier to increase the accuracy of control operation. This study introduces to make a digitally controlled circuit for controlling LED with high-energy efficient by adopting pulse current to LED. The LED current drive system we designed are two systems, the digitally-controlled unit and analog switching mode power supply unit, can be developed separately. The simulation shows the sigma delta modulation of digital to analog converter's output when the input level is 0.7. From this simulation, the output is approached to accurately 0.15% to target value with 510 pulses.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.104-110
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• 2011

High-brightness LED control is required for stable operation, thus the driver and control system must be designed to deliver a constant current to optimize reliability and ensure consistent luminous flux. In this paper, the sliding mode current controller is designed to adjust the illumination density of power LEDs. The controller design model of power LEDs, including its driving circuit, is proposed to realize the dimming control of power LEDs. A buck converter is introduced to drive the power LEDs and reduce the input voltage to a lower level. The sliding mode software controller is implemented to adjust the dimming of power LEDs. The proposed strategy for driving power LEDs is investigated and comparatively studied by experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.572-575
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• 2009

In this study, we proposed WLED(White-Light Emitting Diode) driver IC for mobile applications. This IC drove WLED for mobile applications with low input voltage and high efficiency by using boost converter. The device was designed by using boost converter applied current-mode control algorithm and provided PWM(Pulse Width Modulation) & analog dimming. Designed IC consisted of bias block, drive block, control block, protection block. We confirmed this device worked well through a application PCB (Printed Circuit Board) test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.10
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• pp.65-72
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• 2015

Recently, LED light has been increasingly adopted for vehicles in both domestic and foreign automotive markets, while a variety of LED lights have been developed to be used particularly for headlamps. In this paper, we propose an H-type resonant snubber circuit topology for high efficiency of vehicle LDM (LED Driver Module) and realized LDM functions for vehicle headlamp by designing high-efficiency convertors. In addition, this study reduced the financial burden by configuring the system to control the whole with micom except for the use of individual dedicated chips to drive LED for high and low beam. In order to verify the validity of the proposed H-type resonant snubber capable of soft switching, simulations were performed using PSIM. As a result, the validity was experimentally verified by creating a prototype. Moreover, in order to actually attach the headlamp, the performance of the proposed convertor was confirmed by designing LDM to the limited size. Communications between the headlamp and higher controller were realized using LIN(Local Interconnect Network).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1638-1642
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• 2007

This paper investigated the destruction effect of the semiconductors by impact of high power electromagnetic wave. The experiments is employed as an open-ended waveguide to study the destruction effects on semiconductor using a 2.45 GHz 600 W Magnetron as a high power electromagnetic wave. The semiconductors are located at a distance of $31cm\sim40cm$ from the open-ended waveguide and are composed of a LED drive circuit for visual discernment. Also the chip condition of semiconductor is observed by SEM(Scanning Electron Microscope) analysis. The semiconductor are damaged by high power electromagnetic wave at about 860 V/m. The SEM analysis of the destructed devices showed onchipwire and bondwire destructions. Based on the result, semiconductor devices should have plan to protect the semiconductor devices form high power electromagnetic wave. And the database from this experiment provides the basis for future investigation.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1516-1517
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• 2007

This paper investigated the breakdown effect of the CMOS device by impact of high power electromagnetic wave. The experiments employed a waveguide to study the current characteristics of CMOS device broken by high power electromagnetic wave. The CMOS device were composed of a LED drive circuit for visual discernment. Also CMOS device broken by high power electromagnetic wave was observed by power current. The CMOS device were broke by high power electromagnetic wave at about 10 kV/m and when power current is 75 mA. Based on the result, CMOS devices should show plan to protect the CMOS devices by high power electromagnetic wave. And the database from this experiment should provide the basis for future investigation.