Study Of New Low-power Current-mode Switching Power Supply Circuit

With the development of electric and electronic technology, the electric and electronic equipments have been used broadly in our work and life. Every electronic equipment can not work without reliable power. In 1990s the switching power had been used in all kinds of fields, such as exchanger, communication and control equipments. The core of switching power is control integrated circuits. Because it has the characteristics of high integration, most cost effective, simple periphery circuit and high efficiency. so it has been used broadly. A new type low-power and current-model controller is designed in this thesis. Its operating frequency is 42 kHz, including a power LDMOS which breakdown voltage is 500V. Its output drive current is 110mA, Meanwhile, it works in the skip-cycle mode when the load is light. Its power dissipation is very low. The whole circuit includes Dynamic Self-Supply (DSS) circuit, over current protection circuit and temperature shutdown circuit. The circuit is applied in the products which power from 5w to 100w. This thesis first introduces the basic theory of switching power. The operating theory of this circuit has been demonstrated. The operating principle and simulation analysis about oscillator circuit, reference circuit, temperature shutdown circuit, and voltage regulator circuit have been particularly expounded in the end of this thesis. Simulation results have declared the circuit function has been achieved and the performance characteristics have been obtained...