Browsing by Author "Ehrhart, Andreas"

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Adaptive Pulse Skipping and Adaptive Compensation Capacitance Techniques in Current-Mode Buck-Boost DC-DC Converters for Fast Transient
(2013-01-01)
Ehrhart, Andreas
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Lin, Moris
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Huang, Yung-Sheng
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Lee, Yu-Huei
;
Chen, Ke-Horng
to have a good power management especially for portable devices it is necessary to use the whole battery voltage range (e. g. of Lithium-ion batteries), to provide a fixed output voltage of for example 3V. In this paper a fast transient (FT) current mode buck-boost DC-DC converter with adaptive pulse skipping (APS) and adaptive compensation capacitance (ACC) is proposed. The buck-boost DC-DC converter can work in three different modes, buck, boost and buck-boost. It cannot only use the whole battery range from 2.7V to 4.2V, but also has a good response time with a low voltage undershoot/overshoot at load current variations, due to the APS and the ACC. With the proposed fast transient techniques, improvements could be made in the voltage overshoot/undershoot and the response time. In boost mode, the improvements, in the voltage undershoot and the response time from light-to-heavy load (100mA to 500mA), are 16.7% and 58.8%, respectively. In buck mode, 40% and 49.2% and in buck-boost mode, it is 10% and 63.9%. In case of a load variation from heavy-to-light load (500mA to 100mA), similar results could be reached in every operation mode. The proposed DC-DC buck-boost converter realizes a good power management and a good transient performance to generate a stable supply voltage for portable devices. Its working frequency is 1MHz.
Authentic Mode-Toggled Detector with Fast Transient Response under Wide Load Range Buck-Boost Converter
(2013)
Lin, Moris
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Huang, Yung-Sheng
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Ehrhart, Andreas
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Lee, Yu-Huei
;
Chiu, Chao-Chang
an authentic mode-toggled detector (AMTD) technique is proposed to achieve load and line regulations in a proposed buck-boost (BB) converter. In the case of load transient, conventional BB converter will oscillate and cannot settle to a well-regulated output voltage owing to the on-resistance of the power MOSFETs. Accurate and expeditious mode-toggled detection in the BB converter meet the requirements of load and line transient response by means of the proposed adaptively near-immediate freezer (ANIF) technique. Besides, due to pulse frequency modulation (PFM) implemented in the proposed BB converter, ultra wide load range from 10mA to 900mA can have high efficiency from 80% to 95%. Simulation results show the proposed BB converter fabricated in VIS 0.25 mu m process can be well-regulated under the input voltage ranging from 2.7V to 4.2V.