Research And Design Of COT Loop For Fast Transient Response BUCK Converter

At present,in the field of power management,the traditional linear power supply due to bulky,heavy weight,small power factor and low efficiency has been gradually replaced by switching power supply.In recent years,along with microelectronics technology,magnetic materials research and the level of semiconductor technology continue to optimize and develop,switching power supply technology has made a breakthrough,and has penetrated into all aspects of life.Because the switching power supply has a small size,light weight,low power consumption,transient response speed and other advantages,making a lot of miniaturization of electronic products possible.With switching power supply in the electronic field plays an increasingly important role,people on the switching power supply response speed is getting higher and higher,so how to design a fast transient response of the switching power supply chip has become the people of the current The subject of concern.Based on this background,this paper presents a buck converter with fast transient response characteristics.The Buck converter is used in low-voltage environment,the power tube for the chip integrated,the upper power tube using P-MOS tube,so the drive part of the boot circuit does not have to do,and do not need a minimum turn-off time circuit,greatly simplifies the system circuit design.And the Buck converter is based on the traditional hysteresis mode control mode,the main loop without error amplifier,the system does not need to do zero pole compensation circuit,the circuit stability is high,easy to achieve large bandwidth design,and the system has a very fast load transient response speed.The Buck converter uses internal ripple compensation,the output capacitor using low ESR ceramic chip capacitors,in the realization of high precision output voltage while ensuring the stability of the system work.At the same time,the converter adopts the adaptive on-time modulation method to realize the approximate constant of the switching frequency.In this thesis,0.18?m BCD process is used to simulate the key sub-modules in the system and loop using Cadence's Specter simulation software.The power-on process,continuous mode and intermittent mode Start-up process,load switching,linear adjustment rate and other aspects of the simulation.The overall simulation results show that the Buck converter can achieve constant frequency stabilization at 2.5 ~ 5.5V input voltage,and has a fast load transient response speed,and has a good linear adjustment rate.