Design of implementation the Switched-Capacitor Based Step-Down DC-DC Converter with Improved Voltage Ripple and Load Range

• Main Authors: Kun-jing Liou, 劉昆璟
• Other Authors: Yie-Tone Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/55283253518694490693

碩士 === 雲林科技大學 === 電機工程系碩士班 === 96 === The switched-capacitor DC-DC converter used in the portable electronic devices has the feature: it does not require any inductive elements, so it can be integrated on one chip for reducing the volume and weight. A 5V to 1.1V switched-capacitor DC-DC converter with PFM control is proposed here to achieve a steady output voltage with wide load range. The advantage is through PFM control, the duty cycle of the converter can be fixed to obtain the optimum efficiency even in wide load condition. For PFM control, this thesis uses an error amplifier to sense the output voltage and produce an error signal to change the switching frequency of the converter. Besides, a digital circuit is used to fix the duty-cycle to obtain the best efficiency. This thesis will prove the PFM control has better performance than other control methods. According to the derivation, simulation and experimental results, the output voltage of converter is verified to be nearly steady in 1.1V even with wider load change. The switched-capacitor DC-DC converter with PFM control proposed by this thesis is then proved to be very suitable for the portable electronic products and satisfy the requirement of the low voltage, low power, high efficiency and wide load range.