The Design And Research Of A Boost PFM DC-DC Power Management Chip

A switching power supply has the high level of integration, peripheral circuit issimple, conversion efficiency, the advantages of high in all kinds of electronicproducts widely applied. DC/DC converter is an important branch of the switchingvoltage stabilizer. DC/DC converter has various different forms. Can have the boosttype, step-down type, lift pressure type and so on, also can be divided into isolationtype and the isolation type, according to different method of control and can bedivided into PFM mode, PWM mode and mix modulation pattern, etc. This paperabout UC3500layout design is to use the DC/DC PFM boost mode converter,suitable for light load, has the very high efficiency. But because of the applicationrequirements, the function is a single occasion. Can this chip function expansionthrough, add some function, such as output voltage can have more choices, and toincrease the soft start function to avoid a blunt, overheat, shut off, voltage protection,so that can be used in a wide range of areas.This paper adopts integrated circuit reverse design method design map andcircuit. First analysis of the voltage stabilizer and DC/DC converter, according to thebasic principle of function requirement and performance index, the overall design ofthe circuit; On completing the principle analysis and circuit design, the functionalmodules are done with simulation, analysis and design. Then, the process design andlayout design. Adopt standard CMOS process design circuit, and at the same time useand CMOS process compatible technology made a bipolar transistor, the type canimprove performance, saving chip area, reduce the costs. The simulation resultsindicate that the circuit design meet the requirements of the design, up to the index;Territory design through the DRC and LVS verification.The simulation results show that the design of the system stability, load mapmeet adjustment rate and the response speed of the design demand, very goodrealized system soft start and output filtering inductances charging current limitingfunction, and has good power supply noise and common mode noise suppressionability, tolerance performance is good.