Research On Fast Load Response BUCK DC-DC Converter Based On Capacitor Current Feedback

The microelectronics industry has developed rapidly in recent years and circuit integration is increasing.The performance requirements of various electronic devices on the power supply are more stringent and the research on the design and application of power supply is becoming more and more active.Switching power supply has been widely used due to its advantages of high efficiency,large output power and variable output voltage.On the other hand,with the development of new energy automotive industry and the expansion of intelligent vehicle systems,the vehicle-carry power supply faces new challenges.A fast transient response BUCK DC-DC converter was designed in this paper by introducing the output capacitor branch current as control signal and the hysteresis control method is adopted to improve the transient response speed of system.Firstly,the working principle,control theory,small signal modeling and compensation network design method of BUCK dc-dc converter are introduced and analyzed in detail.Based on the theory of voltage control method,the hysteresis control method of BUCK DC-DC converter with output capacitance current as control signal is proposed.The feasibility and advantages of this method are analyzed theoretically.Then this article embarks from the design requirements to passive components,high-side MOSFET driver circuit,capacitive current feedback control loop,capacitive current detection circuit on PCB and all of the required analog circuits.In order to meet the single power supply in this circuit system the corresponding start-up circuit was also designed.This paper designed a synchronous BUCK DC-DC converter with 10 V~30 V input and 5V output applied to the vehicle-mounted power supply based on 30 V BCD process provided by DB HiTek of Korea.The system does not need an extra low-voltage power supply outside the chip.In order to reduce power consumption,the chip adopts synchronous circuit structure,and the size of power MOSFET is optimized.The hysteresis control method reduces the complexity of the control circuit to achieve higher operating frequency and smaller voltage ripple.The simulation result shows that the design indexes of the converter meet the design requirements.When the load is switched at 800 mA/ns,the transient response time is less than 2 ?s.Finally,the tape-out is carried out after the validation of the layout design and the test work is also in progress.