• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1700-1706
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• 2014

In this paper, a step down converter for LED backlight of mobile application has been proposed. The converter which is operated with 4 MHz high switching frequency is capable of reducing mounting area of passive devices consists of a power stage and a control block. Circuit elements of the power stage are inductor, output capacitor, MOS transistors and feedback resistors. The control block consists of pulse width modulator, error amplifier and oscillator etc. Proposed step down converter has been designed and verified using a $0.35{\mu}m$ 1-poly 4-metal BCD process technology. Simulation results show that the output voltage is 1.8 V in 3.7 V input voltage, output current 100 mA which is larger than 25 ~ 50 mA in conventional 500 KHz driven converter when the duty ratio is 0.4.

• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.411-415
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• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET (metal-oxide semiconductor field effect transistor), inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE, and the PWM controller is implemented to check the operation. In addition, power efficiency is analyzed based on the specification of each component.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.24-31
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• 2008

Power converters are becoming an essential block in modem mobile multimedia application. This paper presents a high performance DC-DC buck converter for mobile applications. Controller of DC-DC buck converter is designed by current-mode control method. An current-mode DC-DC converter is implemented in a standard $0.18{\mu}m$ CMOS process, and the overall die size was $1.2mm^2$. The peak efficiency was 86 % with a switching frequency of $1\sim1.5MHz$ and a maximum load current of 400mA.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.40-42
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• 2019

절연형 전력변환기에서 사용되는 고주파 변압기는 반도체 소자의 스위칭 시간, 전압 강하, 게이트 신호의 불균형 등으로 인해 변압기의 양과 음의 전압-시간(volt-second)에 차이가 발생할 수 있다. 본 논문은 절연형 풀브리지 타입 전력변환기에서 DC 성분에 의한 변압기 코어의 포화문제를 방지하기 위해 사용되는 DC 블로킹 캐패시터(DC blocking capacitor)의 설계 방법에 대해 분석하고 실험을 통해 증명한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1021_1022
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• 2009

본 논문은 친환경 하이브리드 자동차의 높은 배터리 전압을 자동차 전장에 사용할 수 있게끔 낮은 전압으로 변환 시키는 DC-DC 컨버터 회로에 관한 연구이다. 자동차의 전장들이 증가함에 따라 전력변환회로의 용량도 증가하는 추세이며, 높은 용량의 전력변환회로를 구현하기 위하여 풀-브릿지 컨버터 토폴로지를 선택하여 실험 회로를 구현해 보았다. 회로의 효율을 향상시키기 위하여 영전압 스위칭 방식과 동기정류기를 적용하였으며 대전류 출력에 적합한 배전류 정류 회로를 사용하였다. 각각 아날로그 제어 IC와 MCU를 사용하는 두 종류의 800W급 풀-브릿지 DC-DC 컨버터 실험 회로를 제작 후 실험하였으며 MCU를 사용한 디지털 제어를 적용한 실험 회로의 최대 효율이 90.5%로 아날로그 IC를 사용한 실험 회로의 최대 효율 86%보다 높은 것을 확인 할 수 있었다.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.207-210
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• 2002

This paper describes a design of multiple-mode single-output DC/DC converter which can be used in both up and down conversion. Proposed up/down converter does not produce a negative voltage which is generated in conventional buck-boost type converter. Three types of operation mode(up/down/bypass) are controlled by the input voltage sense and command signals of target output voltage. PFM(pulse frequency modulation) control is adopted and modified for fast tracking and for precise output voltage level with an aid of output voltage sense. Designed DC/DC converter has the performance of less than 5 % ripple and higher than 80 % efficiency. Chip area is 3.50 mm ${\times}$ 2.05 mm with standard 0.35 $\mu\textrm{m}$ CMOS technology.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.6
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• pp.461-468
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• 2008

This paper presents a novel series connected DC/DC converter and a proper variable phase shift switching method in order to obtain high voltage ratio for fuel cell system. The proposed series connected DC/DC converter has same rectifier and LC filter for DC output voltage, so it can reduce the number of passive devices regardless of the converter number. In the conventional constant phase shift switching method, the proposed series connected DC converters have inverse bias output voltage. In order to overcome this problem, a simple but proper variable phase shift switching method is proposed in the a novel series connected DC/DC converter. In order to verify the proposed system, simulation and experiments are implemented.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2512-2514
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• 1999

A new zero voltage and zero current switching(ZVZCS) full bridge DC-DC converter with transformer isolation is proposed for arc welding machines. The proposed DC-DC converter uses an auxiliary transformer to obtain ZCS for leading leg, which provides load current control capability even in short circuit condition. The auxiliary circuit also operates in ZVZCS mode. The power rating of the auxiliary transformer is about 10% of the main transformer. The operation is verified by experiments for 12[KW] prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.152-158
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• 1999

Due to high power ratings and low conduction loss, the TGBT has become more attractive in switching power supplies. However, its lower turn-on and turn-off characteristics than those of MOSFET cause severe switching loss and s switching frequency limitation. This paper proposes 2.4kW. 48V. high efficiency half-bridge DC-DC converter using p paralleled TGBT-MOSFET switch concept to use the merits of TGBTs and MOSFETs. Tn parallel switches. each of I TGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by l linearized modelling and the operation of the converter are investigated by simulation results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.197-202
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• 2019

A small millimeter-wave tracking radar power supply must provide stable power with minimal ripple noise and the switching frequency noise of the DC-DC converter must have a real-time self-test capability through on-the-fly monitoring without causing false alarms and ghost In this study, we developed a multi-output switching power supply with output power of more than 80% (@ 100% load) and 10 output power by adopting + 28VDC input for application to small millimeter wave tracking radar, DC-DC converter is applied for large power output and multi-output flyback method is applied for the remaining small power output. The test results show that 85% efficiency efficiency is achieved under 100% load condition.