Study And Design Of High Efficiency And Fast Transience DC-DC Converter

With the popularization and upgrading of electronic equipment,portable electronic products,powered by battery,require more advanced power management technology to ensure the stability,fast load transience and longer operating time.With a flexible output voltage range,a variety of control methods,fast transience response and high efficiency,the DC-DC converter has been more widely used.However,traditional designs with low power consumption can’t achieve faster load transience response,such as current-mode control.A faster transient response converter has complicated control and consumes more power.In order to achieve high efficiency and fast response at the same time,first at all,the loss model of the buck converter was built to figure out optimal sizes of power stage at light load and heavy load.A controller was reused in Pulse Skipping Modulation mode and Pulse Width Modulation mode,which can maintain efficiency at light load and heavy load.Based on the optimal time control,the transient enhanced mode can accelerate transience response.Before the end of transient enhanced mode,output of the controller was predicted and set in a suitable position,so it achieved seamless mode switching.The transient enhanced mode had anti-interference control to avoid false triggers.Moreover,A dynamic bias circuit is designed to disable the power-hungry subcircuits of the controller,reducing static power consumption.The load current change detection used in the system do not need to know the exact value of the parasitic parameters of the capacitor or inductor.The proposed buck converter was implemented in a 0.18μm BCD process to convert an input of 3V-3.6V to an output of 1.8V.When the load current changed between 5m A and 500 m A,the undershoot and overshoot were 26.74 m V and 28.46 m V respectively,and the settling time(1% output voltage droop)was 1.97μs and 1.82μs respectively.The peak efficiency,typical load efficiency(500m A)and light load(5m A)efficiency were 96.6%,94.3% and 86.7% respectively.With a transient enhanced mode,the transience response of the proposed buck converter is faster than traditional current-mode control.The power reduction design can maintain efficiency even at light load.