| Summary: | 碩士 === 國立臺北大學 === 電機工程學系 === 105 === As the development of the portable product market flourishing quickly, modularizing multiple function has become the mainstream. And this also made the power consumption higher, and shorter the battery life. However, portable devices stay in stand-by mode most of the time, through improving light – load efficiency of the converters is efficient to extend its’ battery life. To achieve the conversion efficiency in the wide-load range well, moreover, when in respond to dramatically change, enable to provide stable voltage rapidly. Therefore, fast transient response and smart switching technique are submitted in this thesis.
This thesis presents a wide load range high efficiency buck converter with fast transient response control. In the portion of increasing conversion efficiency, we separate power transistor into two parts, and according to the condition of the load current, open the power transistor correspondingly, which can achieve the optimal switching lose. Besides, improving current sensing circuit enables to detect both power transistors at the meantime, so as to reduce additional V-to-I converting circuit, and to reach the best efficiency effect of power transformation. As for fast transient response control, by changing the output stage of the error amplifier to transfer the output voltage variation to the inner system loop, when the load current changes transiently, it can provide additional compensational current path to the compensational resistor, and change the work period of the buck converter, making output voltage quickly back to stable, and improve the performance of transient response. And this technique is suitable for dynamic voltage scaling techniques usually seen nowadays.
This thesis is implemented with TSMC 0.35um 2P4M 5V CMOS process. The input voltage range of converter is from 2.7V to 4.2V, output voltage set at 1.8V, operating frequency 2MHz, and chip area 1.465 mm^2. The range of load current is 30mA to 600mA and the conversion efficiency is all above 91%. The maximum efficiency will be 95.49% at 250mA. The recovery time of transient response, from light load (50mA) to heavy load (500mA) and heavy load (500mA) to light load (50mA) are 14.8us and 15us, respectively. For what have mentioned above are suitable for the power management of portable electronic products.
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