| Summary: | 碩士 === 國立臺北科技大學 === 電腦與通訊研究所 === 100 === The first part of this thesis presents a low-voltage Li-Ion battery charger which uses multimode with 1.5V supply voltage by using average-current-controlled technique. The proposed charger is operated for trickle current mode, constant current mode, and constant voltage mode, respectively. Using average-current-controlled technique not only prevents sub-harmonic oscillation but also reduces the circuit design complexity. When duty cycle is over 50%, the system still works properly, and does not produce an unstable phenomenon. If the Li-Ion battery occurs short, the driving circuit will enable the short circuit protection to stop charging battery. The low-voltage high-efficiency Li-Ion battery charger using average-current-controlled technique is implemented with TSMC 0.35μm 2P4M CMOS process, and the chip area is 2.46 x 2.68 mm2 (with PADs).
The second part of this thesis presents a high-efficiency hysteresis-current- controlled DC-DC buck converter with over current protection. The buck converter consists of two power transistors, active-current-sensing circuit, sample and hold circuit, hysteresis-current comparator circuit, compensator network, non-overlapping and driving circuit, and over current protection circuit. Generally speaking, the output current of the power management IC exceeds the current limit value will rise the temperature of power transistor, and then causes the power transistor breakdown. In this thesis, the buck converter is limited the ouput current below 650mA by using over current protection for achieving the protective effect and extending the power management IC life cycle. The simulation results show the output voltage is 1.8V when the supply voltage range is 2.5~4.2V. The maximum efficiency is 93.2% when load current is 150mA and supply voltage is 2.5V. The high-efficiency hysteresis-current- controlled DC-DC buck converter with over current protection is implemented with TSMC 0.35μm 2P4M CMOS process, and the chip area is 1.5 x 1.5 mm2.
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