High-speed Load Response Dc-dc Switching Power Supply Ic Design

In recently year,there is a rapid increasing market demanding for battery-powered portable equipments(such as PDAs,Mobiles,etc),which requires the DC-DC converter with high efficiency to boost the battery supply capability and good large signal property to satisfy the special demand of the CPU,DSP and flash memory.We build a high speed load response DC-DC SMPS(Switch Mode Power Supply) IC which is fabricated with 0.6μm CMOS process and integrated with high precision voltage reference,OSC,Slope-compensation function circuit,current limit circuit, current sample circuit,sum-comparator,load regulation integrator and so on.The allowable input voltage ranges from 2.7V to 5.5V and its output voltage can be programmed between 2.7V and 13V,and its operation frequency is 250 kHz.It also has some excellent characteristics,such as lower output ripple,high convert efficiency,and strong ability of load regulation.The SMPS presented by this thesis is based on current control PWM modulation. We use a novel circuit structure in this thesis,which is used to predigest the cascade of error amplifier and PWM comparator used in traditional SMPS:sum-comparator.The sum-comparator can reduce the error and delay caused by the error amplifier in the traditional SMPS.For this,it could improve the speed and precision of PWM modulation and enhance the load response performance.The load regulation integrator is given to eliminate the steady state error in system and enhance the ability of load regulation according to the system demand.In addition,we analyze the stability of the system and the efficiency of the IC carefully.At the end of the thesis,we simulate the whole circuit by Hspice.Through the simulation result,under a typical application,the DC-DC conveter' features show as follows:output voltage ripple is less than 1%,the highest convert efficiency is up to 85%.When the load current step from 10mA to 100mA,the dynamic sag is less than 1%and the fastest restore time is 25μs.In addition,load regulation integrator can enhance the load regulation ability of the system effectively and eliminates the steady state error caused by load regulation.