Research And Design Of Buck DC-DC Converter With Fast Transient Response

The DC-DC converter can adjust the output voltage according to the fluctuation of the input voltage and load current,and has the technical advantages of high conversion efficiency,large input voltage range,and large output current.Large-scale integrated circuits have increasingly higher response speeds for DC-DC converter chips.Therefore,how to design a DC-DC converter chip with fast transient response has become an increasingly important research topic for electronic engineers.The ideal DC-DC converter keeps the same output current as the load current at all times to provide a stable output voltage.However,in practical applications,since the response time of the DC-DC converter when the load current changes is limited,when the load jumps,the output current lags the load current,which causes the output voltage to undershoot or overshoot.If the output voltage varies greatly,it may cause abnormal operation or deteriorate the performance of portable devices.Aiming at the above problems,a design scheme of Buck DC-DC converter with fast transient response is proposed.When the load size changes,the change of feedback voltage is fed back to the oscillator circuit,and the oscillator frequency is changed.The slope of output current is adjusted according to the change of load weight,so as to stabilize the circuit quickly.In addition,the Buck converter current loop stability and voltage loop stability are analyzed.Through the analysis of the system architecture,the specific design scheme of some module circuits is given.The system consists of a fast transient response circuit,a drive circuit,a soft start circuit,an input undervoltage locking circuit and a constant voltage and constant current switching circuit.It has two different working states: constant current output and constant voltage output.The switching circuit ensures the smoothness of the switching.Designed DC-DC converter chip based on 0.18?m BCD process.The Buck type DCDC converter system with fast transient response is simulated and tested.The test results show that when the input voltage of the chip is 12 V and the load current changes within less than 5A,the system conversion efficiency is above 90%,especially when the output current is in the range of 0.3A to 2A,the conversion efficiency is more than 95%,and the load transient response is stable.