The Design Of A High Efficiency Step-up DC-DC Converter

With the development of science and technology revolution, the electronic technology has entered a period of rapid development. Power supply as a source of electronic industry has also entered a stage of rapid development. Currently, the scope of application of power management chip has gone deep into the navigation, mobile communications, consumer electronic and so on. Based on this background and the market demand, the company which I worked as an intern decided to develop a new generation of DC-DC boost converter PT1313.It can meet the market demand of fast charging, when the output voltage is 5V,the maximum output current can reach 1A.The paper introduces the basic principle of Boost DC-DC converter,control mode,modulation mode and system stability firstly,which provide the theoretical guidance for DC-DC boost converter.On the basis of this,it presents the design parameters, including control mode, the specific function of each module,the peripheral parameters and the definition of package pins and so on.In addition to the drive module with the output voltage of power supply,the rest of the modules use the input voltage power supply,and the chip can switch load automatically, so its’ efficiency is high.At the same time,the chip adopts the fixed frequency and peak current control mode,so that the transient response is faster and loop bandwidth is wider;The chip also has short circuit protection,which makes the chip more intelligent,once the circuit is short,it can detect and restart periodic.Then the paper analysis several key modules,the bandgap reference circuit can generate zero temperature coefficient of reference voltage and current,so it can ensure the accuracy of the output voltage and the gain of the amplifier;Due to the built-in power tube,the error amplifier compensates the circuit internally,which can ensure the stability of the system,increase the bandwidth and accelerate the dynamic response;It also analysis the PWM(Pulse Width Modulation Modulation) comparator, oscillator,under voltage lockout and test circuit module.Finally,it simulates the performance and functionality of the system,including the soft-start,short circuit protection,line regulation,load regulation and efficiency.Based on CSMC’s b5212 0.25μm BCD 5v process, the modules and system are simulated in Candence.When the input voltage is 3.7V and the output voltage is 5V,the output voltage ripple is 27 m V;The linear regulation of the system is 2.8%/V;The load regulation of the system is 9.4%/A,the simulation result can meet the design requirements.