Jaeil Baek

This article presents a 48–1 V merged-two-stage hybrid-switched-capacitor converter with a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">linear extendable group operated point-of-load</i> (LEGO-PoL) architecture for ultrahigh-current microprocessors, featuring 3-D stacked packaging and coupled inductors for miniaturized size, fast speed, and vertical power delivery. The architecture is highly modular and scalable. The switched-capacitor circuit

Sinusoidal ripple-current (SRC) charging is a new charging technique that the sinusoidal current superposed with the direct current (dc) charges the battery at the frequency where the battery-alternating current (ac)-impedance reaches a minimum. However, in analyzing the effect on the SRC charging, the dc component of the SRC has not been considered until now. This paper presents a battery impedance analysis when the dc component is considered in the SRC charging. The real battery impedance is a

This paper proposes an interleaved totem-pole bridgeless boost power factor correction (PFC) converter with soft-switching capability. In the proposed converter, an inductor is added compared with the conventional interleaved totem-pole bridgeless boost PFC converter. The added inductor is located between two PFC converter units, and by utilizing the energy of the added inductor, all switches can achieve the zero voltage switching (ZVS). In addition, by applying the phase-shifting control betwee

The half-bridge (HB) LLC converter is one of the most attractive dc-dc converters for medium power supplies due to its soft switching capability. However, its conversion efficiency is considerably degraded in wide-link-voltage applications because of a small magnetizing inductance and wide switching frequency variation for a high voltage gain. In this paper, a boost power factor correction (PFC) stage, which can also play an important role during the hold-up time, is proposed for a high-efficien

In the standby stage of a server power supply, the flyback converter has been widely used due to its simple structure and low cost. However, since the flyback converter suffers from high-voltage stress and a large transformer, it degrades the efficiency and power density of the server power supply. To relieve these drawbacks, this paper proposes a new standby structure where a flyback converter is integrated with a boost power-factor-correction (PFC) converter. The proposed standby structure can

This paper presents a merged-two-stage Linear Extendable Group Operated Point-of-Load (LEGO-PoL) architecture targeting applications with high voltage conversion ratio and very high output current (a few hundreds Amps). In the merged-two-stage LEGO-PoL architecture, many switched capacitor units are connected in series to split the input voltage into multiple voltage domains, and many buck units are connected in parallel to split the output current into multiple current paths. One submodule of t

This paper presents a family of 48 V-1.5 V merged-two-stage hybrid-switched-capacitor converters with a Linear Extendable Group Operated Point-of-Load (LEGO-PoL) architecture for high current microprocessors. The proposed LEGO-PoL converter leverages the advantages of switched-capacitor (SC) circuits and multiphase buck circuits and can achieve soft charging, current sharing, and automatic voltage balancing. The SC circuits are connected in series to split the high input voltage into multiple st

The conventional half-bridge converter for a dc/dc stage in wide-output-voltage and constant-output-current applications such as LED drivers is limited in achieving high efficiency because it is difficult to be designed optimally. To overcome this limitation, an integrated asymmetrical half-bridge zeta converter is proposed for high efficiency in the overall output voltage range. The proposed converter can be simply implemented by replacing a snubber diode with a switch. The proposed converter o

This article presents a reconfigurable voltage multiplying rectifier (RVMR) to improve the performance of an LLC resonant converter for wide output voltage applications. The RVMR can operate as voltage-doubler mode or voltage-quadrupler mode according to the primary switching strategy. Two operation modes split a wide output voltage range into two narrow ranges. Therefore, the RVMR enables the LLC resonant tank to be designed in a narrow output voltage range, which results in a narrow switching

This paper presents a full-bridge active-clamp forward-flyback (FBACFF) converter with an integrated transformer sharing a single primary winding. Compared to the conventional active-clamp-forward (ACF) converter, the proposed converter has low voltage stress on the primary switches due to its full-bridge active-clamp structure, which can leverage high performance Silicon- metal–oxide–semiconductor field-effect transistor (Si-MOSFET) of low voltage rating and low channel resistance. Integrating

The phase-shifted full-bridge (PSFB) converter with synchronous rectifier (SR) is one of the most attractive dc-dc converters for the server power supply due to its high power capability and small secondary ripple current with the output inductor. Moreover, it can more reduce the secondary conduction loss by using parallel-connected mosfets in SR. However, due to large input capacitance of the parallel-connected mosfets in SR, the PSFB converter has large SR gate driving loss, which particularly

This paper presents a modified power factor correction (PFC) ON/OFF control and three-dimensional (3D) printed circuit board (PCB) design for a high-efficiency and high-power density onboard charger (OBC). By alternately operating one of two boost modules of the PFC stage at a 50% or less load condition, the proposed PFC control can reduce the load-independent power loss of the PFC stage, such as core loss and capacitor charging loss of switches. It enables OBCs to have high efficiency across a

This paper presents a merged-two-stage hybrid switched-capacitor point-of-load converter with 3D-embedded coupled inductors, vertical power delivery, and LEGO-PoL architecture. By merging a switched-capacitor circuit with a multiphase buck circuit, the 3D LEGO-PoL converter offers reduced device stress and minimized magnetic size, and enables soft switching, soft charging, voltage balancing, and current sharing. A prototype converter with 3D embedded coupled inductors is designed to deliver powe

Multiphase coupled inductor is a key technology for ripple reduction and fast transient in pulsewidth-modulated power converters. This letter presents the modeling and design of multiphase integrated planar symmetric (MIPS) coupled inductor, together with a hybrid-switched-capacitor dc–dc converter for ultrathin multiphase point-of-load voltage regulation modules. The benefits of MIPS inductors are quantified. A systematic approach to designing high-performance multiphase MIPS inductors is intro

This letter proposes a simple and effective hold-up time extension method for server power systems, in which the fan is only turned off during the hold-up time with ac input loss. Due to the elimination of the fan power in the proposed method, the efficiency of the dc-dc converter increases during the hold-up time; thus, the energy stored in the link capacitor decreases less sharply, compared with the conventional method. That is, the hold-up time can be extended without additional devices, volu