開(kāi)關(guān)穩(wěn)壓器連續(xù)與斷續(xù)模式的區(qū)別及其重要原因

　　開(kāi)關(guān)DC-DC電壓轉(zhuǎn)換器（“開(kāi)關(guān)穩(wěn)壓器”）提供了一些關(guān)鍵優(yōu)勢(shì)，線性穩(wěn)壓器。其中最主要的是效率和靈活性，開(kāi)關(guān)穩(wěn)壓器可以升壓（升壓），降壓（降壓）和逆變電壓輕松。現(xiàn)代模塊化的芯片結(jié)構(gòu)緊湊，可靠，并可從多個(gè)供應(yīng)商（見(jiàn)文章“理解高新區(qū)的優(yōu)勢(shì)和缺點(diǎn)，為一個(gè)完整的線性穩(wěn)壓器”開(kāi)關(guān)和線性穩(wěn)壓器的比較）。

　　然而，這種靈活性是以增加復(fù)雜性為代價(jià)的。對(duì)于一個(gè)熟悉線性調(diào)節(jié)器的優(yōu)雅的工程師來(lái)說(shuō)，設(shè)計(jì)一個(gè)基于開(kāi)關(guān)器件的電源可以有點(diǎn)讓人望而生畏。克服挑戰(zhàn)的關(guān)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.