Design Of A Monolithic BUCK Switching Regulator IC With Proportional Drive Circuit In Peak Current Control Mode

In recent years,with the rapid development of semiconductor technology, a variety of electronic products have been entering people’s daily lives, especially portable products with small size and light weight. However, these electronic products have the problem of low battery utilization and short supply time. Switching power supply has been widely used with its high efficiency, small size and light weight. As an important part of switching power supplies, the DC-DC converter is playing an indispensable role in the process of electronic products towards miniaturization, lightweight and portability.The study of high-performance DC-DC converter has a broad application prospects.Based on peak current control model, using the technology of proportional drive,the thesis designs an integrated circuit used in BUCK type DC-DC converter which has a wide input voltage from 5.5 V to 36 V and low switch on-resistance about 0.1 Ω.The thesis starts with the structure of the BUCK type DC-DC converter, deduces the current waveforms of various components, DC and AC transfer functions and input and output impedance, concludes the small-signal equivalent model. Then, introduces the peak current control mode, analyses the problem of sub-harmonic oscillation, based on which slope compensation technology is introduced, uses the theory of Dr. Raymond B. Ridley build the complete small-signal equivalent model containing control loop.Next, the bipolar power transistor has been systematically studied, including analysis of switching process, comparison of resistive load and inductive load, introduction of several anti-saturation configurations and four kind of drive circuits, which is instructive to the design of drive circuit. After that, modules in the chip are designed and simulated to verify the design scheme. At last, the outer components of converter are chosen and the complete circuit is simulated.Simulation based on CSMC 2 μm 36 V bipolar process showed that the IC operates normally within 5.5 V~36 V inputs, the on–resistance of power switch is only 0.1 Ω and the drive circuit has no static off power dissipation.