A Design Of Hystersesis Buck DC-DC Converter

In recent years,with the rapid growth of portable electronic products,the matching power management system also has a more and more widely market.Duing to its advantages such as high efficiency,small weight and volume,DC-DC converters are widely used in many electronic systems,it is the key point for many circuits whether it can work properly. Due to a late start,domestic design level lagged far behind foreign advanced level,based on this background, we began to study and design advanced DC-DC converters.According to the design needs,the specifications of the DC-DC converter were presented.Combined with the actual situation, a Buck topological structure were used in this system.This paper analysed the structure characteristics of several kinds of feedback control model,the system with hysteresis comparator is pointed out to have good stability.We used the hystersesis comparator, and analysed the existing problems in loop control.The DC-DC converter consists of hysteretic comparator(HC), bandgap reference voltage source(BGR),linear regulator(LDO),over-current protection circuit(OC) and over-temperature circuit(OTP) and so on. In order to realize high precision, fast loop control, this paper designed high and low side control circuit with high precision and low power consumption.By using Hspice,the system and its sub-module circuits were simulated. The simulation results show that with the minimum input voltage 5V, the converter’s output voltage can range from 0.5V-2.5V,the maximum load current is up to 1.5A.Output ripple voltage is below 42 mV for nominal condition, line regulation is 25 mV/V load regulation is 0.5% at 100 mA current step. With the advantages of high efficiency,fast output load transient response and so on, the designed DC-DC converter can satisfy the initial design specification. Finally summarized in encounter and overcome the difficulty in the circuit design, and put forward the prospect for the future.