Design Of A Single Inductor Dual Output DC-DC Converter With Wide Load And High Efficiency

In recent years, SIDO converter has been widespread concern in power management area due to the reduction of off-chip inductor, cost and complexity. The converter with multiple modes control which can be more flexible and effective for Soc power management systems has become a research trend. However, there are problems in SIDO converter such as limited load range and low efficiency which hinder its developmentIn this thesis, a novel adaptive PWM/PSM switching mode control SIDO converter with wide load range and high efficiency is proposed. This thesis firstly researched the converter’s loss including switching loss and conduction loss. The optimal switching point is obtained by the relationship between the converter’s loss and different loads. Dynamic shutdown stategy is proposed to reduce the static power consumption. According to the different loads of two outputs, the loads are divided into both heavy loads range, both light load range, one heavy load range and the other light load range in order to increase the converter’s efficiency. Also, the proper control mode with different load range is determined. To realize the adaptive switching mode, the load detection circuit including the zero detection circuit and secondary duty detection circuit, the mode switching circuit to automatically adjust the converter’s different working modes are proposed. Based on CHART 0.18μmCMOS process, this thesis provides the layout design and post layout simulation.The post layout simulation indicated that the proposed SIDO converter provided two wide load ranges from OmA to 250mA. The peak efficiency of the converter is 91% in heavy loads while the whole efficiency is over 84% in light loads. The output ripples are both less than 10mV in PWM mode control while in PWM/PSM switching control mode the two outputs ripples are less than 30mV. All the results basically meet the requirements.