A Dc Power Conversion Circuit Research And Design

Switching power supplies were widely used because of high efficiency and small bulk. A dual step-up DC/DC converter using 1.5 micro-meter BiCMOS/DMOS process with wide input voltage range of 2.7V to 5.5V was presented on this thesis. The converter was designed to drive up to a 5 white LEDs with a constant current when the device operates with pulse width modulation (PWM) and to power an organic LED display with a constant voltage when the circuit operates in pulse frequency modulation (PFM) for higher efficiency. Output over-voltage protection and a 1MHz switching frequency allow for the use of small, low cost external components. Additional features include current mode, current-limit, over temperature protection, input under-voltage protection and so on.First, the operational principle of the Boost converter which includes continuous mode and discontinuous mode was analyzed as well as the basic theory about current mode and the circuit modulation which includes Pulse Width Modulation (PWM) and Pulse Frequency Modulation (PFM).Second, the theory of sub-block circuits which include Bandgap voltage reference, Over Temperature Protection, output Over Voltage Protection and input Under Voltage Protection was analyzed and these sub-block circuits were simulated using HSPICE. Some characteristic simulation of the whole circuit were finished and analyzed later. The efficiency of the Boost converter achieves 80%. The characteristics of the circuit structure were analyzed and the author summarized his own work in the ends of this paper.Base on the Boost principle analysis and circuit design in the beginning, the author simulated the sub-block circuits and whole chip circuit by applying EDA tools HSPICE, the simulation result indicates that the IC has achieved the expectation of the function target and the electrical characteristics. Although there were unavoidable disadvantages of this project, it is a worthwhile and valuable experience.