An Integrated Buck Converter And Linear Regulator, Multi-output Dc-dc Converter Design

In today's consumer market, electronic devices are in great demand. With more and more functions integrated in these devices, power management integrated circuits such as DC-DC converters with higher performance are mandatory. In order to meet the requirements, a multiple-output DC-DC converter integrated with step-down converter and linear regulator controllers is designed in this thesis. It is based on UMC 0.6μm BCD process, and integrated an internal linear-regulator, one step-down converter and three low dropout linear regulators. When it is shut down, the step-down regulator and all linear regulators are turned off, but the internal linear-regulator and internal reference remains active. An internal linear regulator provides MOSFET gate drive and can be used to power small external loads. Soft-start functions to limit inrush current during startup. A programmable startup sequence enables easy control of the regulators, it also includes an open-drain timed microprocessor supervisor function to ensure proper startup of digital circuits. It operates in wide input voltage range from 4.5V to 28V. This converter can operate in the temperature rage of -25℃to 85℃. It is suitable for LCD monitor and TV applications running directly for AC/DC wall adapters.In this thesis, basic principles and some key points of a DC-DC converter were given firstly. Then, the whole chip diagram was proposed according to the design specification and the whole chip operational principle was introduced. Based on the whole chip function requirements, sub-block design and simulation were completed. Since the chip was accomplished through the team work, the author paid particular attention to the analysis of the whole chip architecture and the design of the following sub-blocks, including bandgap voltage reference, current reference, reset and startup sequence. At last, the whole chip function simulation and typical performance characteristics simulation were presented. In the conclusion of this thesis, the research value of this circuit was pointed out, but it was suggested that corner simulation and post-layout simulation should be indispensable.This thesis is a production of circuit principles and simulation practice. Based on the circuit principle analysis, the author simulated the sub-block circuits and the whole chip circuit by applying the EDA tool HSPICE. The simulation results indicate that the converter has achieved the design specification. Furthermore, the circuit principle analysis has been verified.