| The Internet of things,portable electronic devices,data centers and artificial intelligence devices are becoming more and more powerful and complex.The power management chip needs smaller volume while providing efficient and stable power.With the advantages of high power density,high energy conversion efficiency and flexible topology,DC-DC converters are widely used in such applications.In order to meet the low and medium voltage applications such as long-time high-efficiency light load standby,fast wake-up and high current supply,this kind of converter based on V2 current mode and ripple control is produced.This paper designs two Buck converter chips and one LDO chip for the power supply requirements of high light-load efficiency,high precision and fast transient response of the power supply of the Internet of Things,portable electronics and data center equipment.The first buck chip is based on current mode cot topology.Before the specific circuit design,this paper analyzes the development requirements of converter control strategy,and establishes the mathematical models of peak current mode,cot current mode and rbcot mode through the description function method.After comprehensively considering various application conditions,cot current mode and rbcot become the control methods of this chip design because of their high efficiency and fast response.The first current mode synchronous buck chip based on COT is designed for high current applications such as data center.It has a stable and simple compensation loop.A single chip can work well in the input range of 5-36 V,0-5A and up to 1MHz.It can also realize multi-phase and multi chip parallel connection through PLL(Phase Locked Loop)to provide more current.The second synchronous buck converter based on Ripple-COT can output 0.8-7V,0-2A and 700 k Hz operating frequency for portable electronics and Internet of things devices,which need high light load efficiency and fast transient response.With the valley sample and hold technology proposed in this paper,it is compatible with low ESR capacitors,which is more conducive to further reducing the size of peripheral devices.The core power supply LDO module used in these two kinds of buck can provide a stable power rail for the sub modules that keep switching working state in the chip with its high bandwidth and excellent regulation ability.The LDO architecture is excellent,and it can also be used as a DC-DC post stage power supply to provide a low noise and stable power rail for the equipment sensitive to power noise.The two buck converters designed in this paper are simulated and verified by Simplis and spectre software,and then the 0.35 μm BCD process is used to tape them.In addition,the core power supply LDO module uses 0.18 μm BCD process to verify its function as DC-DC post stage power supply. |
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