開關電源不同于線性電源適配器，前(qian)者調(diao)整管工(gong)作(zuo)在(zai)(zai)通、斷狀態，后者調(diao)整管工(gong)作(zuo)在(zai)(zai)線性狀態。電(dian)(dian)(dian)源(yuan)(yuan)適配器(qi)通過控制(zhi)調(diao)整管的(de)通、斷時(shi)間實現(xian)穩壓。電(dian)(dian)(dian)源(yuan)(yuan)適配器(qi)的(de)優點是(shi)體積小(xiao)(xiao)(xiao)、重(zhong)量輕、功耗小(xiao)(xiao)(xiao)、穩壓范圍(wei)寬(kuan)，效率(lv)可(ke)高達80%～90%。調(diao)整管功率(lv)損耗小(xiao)(xiao)(xiao)，散熱器(qi)也隨之(zhi)減(jian)小(xiao)(xiao)(xiao)。英規(gui)電(dian)(dian)(dian)源(yuan)(yuan)適配器(qi)工(gong)作(zuo)頻率(lv)在(zai)(zai)幾十千赫(he)茲(zi)甚至(zhi)幾百(bai)千赫(he)茲(zi)，濾波電(dian)(dian)(dian)感、電(dian)(dian)(dian)容(rong)元件可(ke)用較小(xiao)(xiao)(xiao)的(de)容(rong)量，允許的(de)環境(jing)溫(wen)度也可(ke)以大(da)大(da)提(ti)高，廣泛應用在(zai)(zai)各種電(dian)(dian)(dian)子設(she)備中。本(ben)(ben)章(zhang)主要介紹(shao)電(dian)(dian)(dian)源(yuan)(yuan)適配器(qi)的(de)基本(ben)(ben)構成、分類及工(gong)作(zuo)原理，讓讀(du)者對電(dian)(dian)(dian)源(yuan)(yuan)適配器(qi)有一個初步(bu)的(de)認識(shi)。

　　穩壓電源適配器的比較

　　電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)設備(bei)(bei)離不開電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)。電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)供給電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)設備(bei)(bei)所需(xu)要(yao)的(de)(de)能量(liang)(liang)。電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)的(de)(de)性(xing)(xing)能、質量(liang)(liang)直接影響著(zhu)電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)設備(bei)(bei)的(de)(de)安全(quan)可靠運行，故此(ci)對電(dian)(dian)(dian)(dian)(dian)子(zi)(zi)設備(bei)(bei)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)性(xing)(xing)能、質量(liang)(liang)的(de)(de)要(yao)求也(ye)越來越高(gao)。現有(you)(you)的(de)(de)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)主要(yao)有(you)(you)兩(liang)大類：串聯線性(xing)(xing)穩壓電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)(簡稱線性(xing)(xing)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi))和(he)開關穩壓電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)(簡稱電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi))。這兩(liang)類電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)(pei)(pei)器(qi)各具特色而被廣(guang)泛應用。

　　線性電源適配器的結構與特點

　　線性(xing)電源適配器通常都是由電網所提供的交流(liu)電，經(jing)過變壓、整流(liu)、濾(lv)波和(he)穩壓環(huan)節(jie)而得(de)到(dao)。其(qi)各個部分電路的作用(yong)如下：

　　①電(dian)(dian)(dian)源適配器(qi)變(bian)壓(ya)器(qi)——將220V電(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)壓(ya)轉換為整(zheng)流電(dian)(dian)(dian)路(lu)所需要(yao)的交流電(dian)(dian)(dian)壓(ya)值，而少部分電(dian)(dian)(dian)路(lu)采用電(dian)(dian)(dian)容降(jiang)壓(ya)，如遙控(kong)電(dian)(dian)(dian)風扇電(dian)(dian)(dian)路(lu)。

　　②整(zheng)(zheng)流(liu)(liu)電(dian)路——將交流(liu)(liu)電(dian)壓轉(zhuan)換為(wei)脈動直流(liu)(liu)電(dian)壓。常(chang)用的整(zheng)(zheng)流(liu)(liu)電(dian)路有半波整(zheng)(zheng)流(liu)(liu)電(dian)路、全波整(zheng)(zheng)流(liu)(liu)電(dian)路和橋式(shi)整(zheng)(zheng)流(liu)(liu)電(dian)路。

　　③濾波電(dian)路——將脈動直(zhi)流(liu)電(dian)壓轉換成較為平滑的(de)直(zhi)流(liu)電(dian)壓。線(xian)性電(dian)源適配(pei)器中(zhong)常用(yong)的(de)濾波電(dian)路有電(dian)感濾波、電(dian)容(rong)濾波和阻容(rong)濾波，其(qi)中(zhong)最常用(yong)的(de)是電(dian)容(rong)濾波。

　　④穩(wen)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)——將(jiang)直流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)適配器的(de)(de)輸出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)穩(wen)定，基(ji)本不受電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網(wang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)或負載的(de)(de)影響(xiang)。在線性電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)適配器中(zhong)常用的(de)(de)穩(wen)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)有(you)二極管(guan)穩(wen)壓(ya)(ya)(ya)、串(chuan)聯(lian)穩(wen)壓(ya)(ya)(ya)。其中(zhong)，串(chuan)聯(lian)穩(wen)壓(ya)(ya)(ya)有(you)現成(cheng)(cheng)(cheng)的(de)(de)集(ji)成(cheng)(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)，如固定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)輸出的(de)(de)集(ji)成(cheng)(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)有(you)LM78××，LM79××等，可調電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)輸出的(de)(de)集(ji)成(cheng)(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)有(you)LM317和LM337等。

　　4個功能模塊的線性穩壓電源適配器

　　線(xian)性電源(yuan)適配器(qi)的優(you)點是穩定性好、瞬態(tai)(tai)響(xiang)應速度(du)快、可靠性高、輸(shu)(shu)出電壓(ya)精(jing)度(du)高和(he)輸(shu)(shu)出紋波電壓(ya)小;缺點是工作(zuo)頻率低(di)，所采用的工頻變壓(ya)器(qi)、濾波器(qi)的體積和(he)重量(liang)都較大。調整(zheng)管工作(zuo)在線(xian)性狀態(tai)(tai)，功耗大、效率低(di)，需要加裝散熱器(qi)。