Research And Design Of Switching Mode Power Supply With Wide Output Voltage Range

Nowadays,electronic products have greatly enriched people's live,also the demands for which are becoming higher and higher.Only through continuously improving the function and performance of electronic products can we make people's needs being met.Switching mode power supply plays an important role in electronic products.There are still deficices in the efficiency,stability and output voltage of traditional power management chips.Therefore,the continuous optimization of a switching mode power supply in these areas not only has certain practical significance,but also can make it deal with the challenges of the development of electronic products.In this thesis,the principle of boost DC-DC converters is introduced in detail,and the corresponding theoretical deduction is also given.On this basis,the boost DC-DC converter XD1797 is designed.In terms of performance,through analyzing the factors that influence efficiency,we design the power switch,choose the peripheral devices and the switching frequency of the chip reasonably,which improve the efficiency of the chip and ensure high efficiency when the chip is in light load,with a wide output voltage range achieved.In terms of structure,the DC-DC converter adopts the peak current feedback control mode to improve the transient response speed.The PWM modulation is adopted and the output capacitor is selected reasonably to achieve smaller output voltage ripple.The frequency selection signal is added so that the switching frequency of the converter can be chosen according to the different selection signal.In stability,an analysis of the stability of the current loop and the voltage loop is made.For the current loop,a slope compensation circuit is designed to prevent the subharmonic oscillationin in the peak current mode.For the voltage loop,an error amplifier with Type2 A compensation is adopted to avoid the influence of the system power level on the stability of the loop,with the phase margin of the loop and the system's stability improved.In addition,the over-current protection circuit,over temperature protection circuit,undervoltage latch circuit and other protection circuits are designed to avoid the over-current,over temperature,undervoltage and other abnormal conditions respectively on the chip which may damage the chip,thus the using time of the chip is prolonged.XD1797 has been implemented by a 0.18?m 40 V BCD process and is simulated by Hspice simulator in the Cadence.The simulation results show that the chip can achieve a wide output voltage range,which is 2.9V~36V.The efficiency of the converter can exceed 90% when the output voltage is typical 13.6V,with small output voltage ripple and fast transient response achieved.In addition,the chip has good load regulation and linear regulation.