開關穩(wěn)壓器連續(xù)與斷續(xù)模式的區(qū)別及其重要原因

　　開關DC-DC電壓轉換器（“開關穩(wěn)壓器”）提供了一些關鍵優(yōu)勢，線性穩(wěn)壓器。其中最主要的是效率和靈活性，開關穩(wěn)壓器可以升壓（升壓），降壓（降壓）和逆變電壓輕松。現代模塊化的芯片結構緊湊，可靠，并可從多個供應商（見文章“理解高新區(qū)的優(yōu)勢和缺點，為一個完整的線性穩(wěn)壓器”開關和線性穩(wěn)壓器的比較）。

　　然而，這種靈活性是以增加復雜性為代價的。對于一個熟悉線性調節(jié)器的優(yōu)雅的工程師來說，設計一個基于開關器件的電源可以有點讓人望而生畏。克服挑戰(zhàn)的關鍵是了解什么是發(fā)生在里面的小芯片。

　　The most fundamental principle of the switching regulator’s operation is that it derives its voltage regulation from the high-frequency switching of a metal-oxide semiconductor field-effect transistor （MOSFET）， controlled by pulse-width modulation （PWM）， feeding its energy to an inductor. The inductor then acts as an energy reservoir supplying current during the period that the MOSFET is “OFF”。

　　Transistor switching is a clever method of regulating a voltage and results in a switching regulator exhibiting efficiency from 80 to 95 percent or even greater. The downside is the switching adds noise （ripple） to the voltage output and is responsible for introducing much of the complexity to the design process because it introduces electromagnetic interference （EMI） problems.