AC/DC開關電源適配器(qi)芯片（或稱模塊），只(zhi)要配合(he)一些阻容元件和一個開(kai)關(guan)變(bian)壓(ya)器，就可以做成一個基(ji)本的開(kai)關(guan)電源適配器。

普通(tong)(tong)半橋(qiao)(qiao)(qiao)(qiao)(qiao)開(kai)(kai)關電(dian)(dian)(dian)(dian)源適配器的主要(yao)工(gong)作原理(li)就是上(shang)(shang)橋(qiao)(qiao)(qiao)(qiao)(qiao)和下(xia)橋(qiao)(qiao)(qiao)(qiao)(qiao)的開(kai)(kai)關管（頻(pin)率高時(shi)開(kai)(kai)關管為(wei)VMOS）輪流(liu)導(dao)通(tong)(tong)，首先(xian)電(dian)(dian)(dian)(dian)流(liu)通(tong)(tong)過上(shang)(shang)橋(qiao)(qiao)(qiao)(qiao)(qiao)開(kai)(kai)關管流(liu)入(ru)，利(li)用電(dian)(dian)(dian)(dian)感(gan)線圈(quan)(quan)的存(cun)儲(chu)功能，將電(dian)(dian)(dian)(dian)能集聚在線圈(quan)(quan)中，最后關閉上(shang)(shang)橋(qiao)(qiao)(qiao)(qiao)(qiao)開(kai)(kai)關管，打開(kai)(kai)下(xia)橋(qiao)(qiao)(qiao)(qiao)(qiao)的開(kai)(kai)關管，電(dian)(dian)(dian)(dian)感(gan)線圈(quan)(quan)和電(dian)(dian)(dian)(dian)容持續給(gei)外部供電(dian)(dian)(dian)(dian)。然后又關閉下(xia)橋(qiao)(qiao)(qiao)(qiao)(qiao)開(kai)(kai)關管，再打開(kai)(kai)上(shang)(shang)橋(qiao)(qiao)(qiao)(qiao)(qiao)讓電(dian)(dian)(dian)(dian)流(liu)進(jin)(jin)入(ru)，就這樣重復進(jin)(jin)行。因(yin)為(wei)要(yao)輪流(liu)開(kai)(kai)關兩開(kai)(kai)關管，所以稱為(wei)開(kai)(kai)關電(dian)(dian)(dian)(dian)源適配器。

作為AC-DC類電(dian)源(yuan)適配器中的開關電(dian)源(yuan)IC。AC/DC開關電(dian)源(yuan)適配器的主要優點：

a:體積小、重量輕（體積和重量只有線性電(dian)源適(shi)配器(qi)的20%～30%）、

b:效(xiao)率高(gao)（一般(ban)為60%～70%，而(er)線性電(dian)源適配(pei)器只有30%～40%）、

自身抗干(gan)擾性強、輸出電壓范圍(wei)寬、模塊(kuai)化。

常用的低壓(ya)(ya)(ya)(ya)AC開關電(dian)源適(shi)配器(qi)將220VAC電(dian)經過(guo)EMI濾波器(qi)后直(zhi)接整(zheng)流成300V左右的AC電(dian)壓(ya)(ya)(ya)(ya)，通過(guo)電(dian)路控(kong)制(zhi)開關管進行(xing)高(gao)速的導通與截(jie)止(zhi)再轉化為高(gao)頻(pin)率(lv)的AC電(dian)提(ti)供給(gei)變(bian)壓(ya)(ya)(ya)(ya)器(qi)進行(xing)變(bian)壓(ya)(ya)(ya)(ya)，從而(er)產生所需(xu)要(yao)的一組(zu)或(huo)多(duo)組(zu)電(dian)壓(ya)(ya)(ya)(ya)，而(er)后再整(zheng)流成所需(xu)要(yao)電(dian)壓(ya)(ya)(ya)(ya)的AC電(dian)。