Design Of Synchronous Rectification DC-DC Boost Converter In PFM Mode

With the continuous development of electronic equipment,the power supply must be constantly improved to the direction of high precision,high efficiency,high integration,low power consumption and low cost for the porpose of the miniaturization of equipment volume and the high efficiency of performance.Among them,switching power supply with high efficiency,small size,wide voltage range and other advantages gradually become the mainstream.Since the light load is the frequent application of switching power supply,it is of practical significance to study the efficiency of DC-DC converter under the light load.In this thesis,a PFM mode synchronous rectifier DC-DC booster converter chip is designed.The modulation is carried out by using the current limiting PFM mode.The switching power supply is controlled by the current limiting method.The integrated power switch N-type MOSFET and synchronous rectifier P-type MOSFET have the advanthges of low on-resistance.The minimum on-time control module is also designed to make the on-time adaptive adjustment according to the input and output voltage,hence the designed circuit has certain adaptability.Peripheral components are only composed of one inductance and two capacitors.Under the light load,the proposed DC-DC booster converter shows the advantages of fast load transient response,low output ripple and high efficiency.The proposed DC-DC booster converter in this thesis is simulated by using the Cadence spectre platform to carry out the functional verification of the circuit module,and the process model of CMOS 0.35 μm is adopted to finally realize and test the chip.The input voltage ranges from 0.9V to 3.3V,and the output voltage can be adjusted through the internal feedback resistance,ranging from 1.8V to 5.0V,the typical value of the output voltage is 3.3V.The experiment results show that the static current is about 6.6μA and the output ripple is less than 60 mV.Besides,the load adjustment rate and the linear adjustment rate are also promising.Under the light load conditions,the overall conversion efficiency is more than 85%.The proposed DC-DC boost converter shows great potential in the applications include mouse,keyboard,low-power wireless device,game controller and home medical equipment.