A High-efficiency Step-down DCDC Power Supply Design

This paper mainly discusses the design and implementation of a DC/DC regulator under BCD technology.The structure of the BUCK type DC/DC is mainly used in this paper.In this paper,the basic principle and control mode of the Buck DC/DC converter are carefully studied.It provides theoretical guidance for the design and implementation of this chip,and designs an efficient step-down converter,which uses the PWM peak current mode modulation scheme,making the chip able to change when the power supply voltage or load changes.Fast response and high efficiency,using the piecewise linear slope compensation circuit to eliminate the open loop instability in the current mode DC/DC converter when the duty ratio is greater than 50%,the response is not ideal,and the noise sensitivity and so on.The chip uses a fixed frequency of 140 khz internal oscillator and high order temperature compensated voltage reference.The reference temperature drift coefficient is less than 7ppm,and the chip also integrates overvoltage,over temperature,over current protection module and linear soft start module to prevent the inductor surge current caused by the chip when it starts or closes.Combined with performance requirements and cost considerations,this chip has designed a working range that can work at the input voltage from 4V to 23 v,with a minimum output voltage of 0.9V and a continuous load current of 3A.The module analysis and design work of the related subunits are completed,and the function verification is carried out with the cadence software.After the simulation of the whole circuit,the layout of some sub circuit modules is also carried out.