| Summary: | 博士 === 國立交通大學 === 電控工程研究所 === 105 === Nowadays, the market requires lots of products manufactured with tablet mobile devices, and requires more and more functions in the display panels. In the display panel of tablet mobile devices, power management system prefers to using power management circuit chip, which means that the system integrates several power units in a chip, such as buck and boost DC-DC converters. However, with limited battery capacity and low efficiency of handheld devices, operation voltage of display circuits has to be lowered to decrease the consumption, and to keep the battery running longer. Meanwhile, when operation voltage is lowered, decreasing the disturbance of output voltage in the corresponding buck converter is very important. Since excessive disturbance of output voltage may cause the system abnormal. Besides, in the display system of handheld devices, decreasing the disturbance of output voltage variation in the boost converter is very important as well, because excessive disturbance of output voltage will degrade the display quality, and lead to bad experience of the products.
Therefore, this thesis is about the improvement of output voltage variation in the buck and boost converters which are applied in tablet display system. Low output voltage variation will be achieved in buck converter by proposed valley detection and overshoot reduction technique. And, based on the hysteresis current control, duty cycle will be controlled by proposed technique in the transient state. Therefore, output voltage variation of load transient state in boost converter can be reduced efficiently. The experiment result shows load regulation can be improved to 3mV, and output voltage variation can be decreased to lower than 10%, about 93mV in buck converter. Moreover, the output voltage variation of boost converter can be lowered to 30% and 44%, compared to conventional control during load from light to heavy and heavy to light, respectively
|
|---|
