開關電源不同于線性電源適配器，前者調整(zheng)(zheng)管工(gong)作(zuo)在(zai)通、斷(duan)狀態，后者調整(zheng)(zheng)管工(gong)作(zuo)在(zai)線性狀態。電(dian)(dian)(dian)源(yuan)適配器(qi)(qi)通過控制調整(zheng)(zheng)管的(de)通、斷(duan)時間實現穩壓。電(dian)(dian)(dian)源(yuan)適配器(qi)(qi)的(de)優(you)點是體積小(xiao)、重量(liang)輕、功(gong)耗小(xiao)、穩壓范(fan)圍(wei)寬，效率可(ke)高達80%～90%。調整(zheng)(zheng)管功(gong)率損耗小(xiao)，散(san)熱(re)器(qi)(qi)也隨(sui)之(zhi)減小(xiao)。英規電(dian)(dian)(dian)源(yuan)適配器(qi)(qi)工(gong)作(zuo)頻率在(zai)幾十千赫茲(zi)甚至幾百千赫茲(zi)，濾波(bo)電(dian)(dian)(dian)感、電(dian)(dian)(dian)容元(yuan)件(jian)可(ke)用(yong)較小(xiao)的(de)容量(liang)，允許的(de)環境溫度(du)也可(ke)以(yi)大(da)大(da)提高，廣泛(fan)應用(yong)在(zai)各種電(dian)(dian)(dian)子設備中。本章主(zhu)要介(jie)紹電(dian)(dian)(dian)源(yuan)適配器(qi)(qi)的(de)基本構(gou)成、分類及工(gong)作(zuo)原理，讓讀者對(dui)電(dian)(dian)(dian)源(yuan)適配器(qi)(qi)有(you)一個初步的(de)認識。

　　穩壓電源適配器的比較

　　電(dian)(dian)(dian)(dian)子(zi)設(she)備(bei)離不開電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)。電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)供給電(dian)(dian)(dian)(dian)子(zi)設(she)備(bei)所(suo)需(xu)要(yao)的(de)(de)能量(liang)(liang)。電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)的(de)(de)性(xing)能、質(zhi)量(liang)(liang)直接影(ying)響著電(dian)(dian)(dian)(dian)子(zi)設(she)備(bei)的(de)(de)安全可靠運行，故此對電(dian)(dian)(dian)(dian)子(zi)設(she)備(bei)電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)性(xing)能、質(zhi)量(liang)(liang)的(de)(de)要(yao)求也越來越高。現有的(de)(de)電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)主要(yao)有兩大類(lei)(lei)：串聯線性(xing)穩壓電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)(簡(jian)稱線性(xing)電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi))和開關穩壓電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)(簡(jian)稱電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi))。這兩類(lei)(lei)電(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)(shi)(shi)(shi)(shi)配(pei)(pei)器(qi)各具特色(se)而被廣泛應用。

　　線性電源適配器的結構與特點

　　線(xian)性電(dian)源適(shi)配器通常都是(shi)由電(dian)網所(suo)提供的交流(liu)(liu)電(dian)，經過變壓(ya)、整流(liu)(liu)、濾波和穩壓(ya)環節而得到。其(qi)各個部分(fen)電(dian)路的作用(yong)如下(xia)：

　　①電(dian)(dian)源適(shi)配器變壓器——將220V電(dian)(dian)網電(dian)(dian)壓轉換為整(zheng)流電(dian)(dian)路所需要的交流電(dian)(dian)壓值，而少部(bu)分(fen)電(dian)(dian)路采用(yong)電(dian)(dian)容降壓，如遙控(kong)電(dian)(dian)風扇電(dian)(dian)路。

　　②整流電路(lu)——將交流電壓轉換為脈動(dong)直(zhi)流電壓。常(chang)用的整流電路(lu)有半(ban)波整流電路(lu)、全波整流電路(lu)和橋(qiao)式整流電路(lu)。

　　③濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)路——將脈動直流電(dian)(dian)(dian)壓轉換成較(jiao)為平滑的(de)直流電(dian)(dian)(dian)壓。線性電(dian)(dian)(dian)源適配(pei)器中常(chang)用的(de)濾(lv)(lv)(lv)波(bo)電(dian)(dian)(dian)路有(you)電(dian)(dian)(dian)感濾(lv)(lv)(lv)波(bo)、電(dian)(dian)(dian)容(rong)濾(lv)(lv)(lv)波(bo)和(he)阻容(rong)濾(lv)(lv)(lv)波(bo)，其中最常(chang)用的(de)是電(dian)(dian)(dian)容(rong)濾(lv)(lv)(lv)波(bo)。

　　④穩(wen)壓(ya)(ya)(ya)電(dian)(dian)(dian)路(lu)——將直流電(dian)(dian)(dian)源(yuan)適配器(qi)的(de)(de)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)(ya)(ya)穩(wen)定，基本不受電(dian)(dian)(dian)網電(dian)(dian)(dian)壓(ya)(ya)(ya)或(huo)負載的(de)(de)影響。在線性(xing)電(dian)(dian)(dian)源(yuan)適配器(qi)中(zhong)常用的(de)(de)穩(wen)壓(ya)(ya)(ya)電(dian)(dian)(dian)路(lu)有二極管穩(wen)壓(ya)(ya)(ya)、串(chuan)聯穩(wen)壓(ya)(ya)(ya)。其中(zhong)，串(chuan)聯穩(wen)壓(ya)(ya)(ya)有現(xian)成(cheng)的(de)(de)集成(cheng)電(dian)(dian)(dian)路(lu)，如固定電(dian)(dian)(dian)壓(ya)(ya)(ya)輸(shu)出(chu)的(de)(de)集成(cheng)電(dian)(dian)(dian)路(lu)有LM78××，LM79××等，可調電(dian)(dian)(dian)壓(ya)(ya)(ya)輸(shu)出(chu)的(de)(de)集成(cheng)電(dian)(dian)(dian)路(lu)有LM317和LM337等。

　　4個功能模塊的線性穩壓電源適配器

　　線性(xing)電源適(shi)配(pei)器的優(you)點(dian)是穩定性(xing)好、瞬態響(xiang)應速度快(kuai)、可靠(kao)性(xing)高(gao)、輸出(chu)電壓(ya)精度高(gao)和輸出(chu)紋(wen)波電壓(ya)小;缺點(dian)是工(gong)作(zuo)頻率低，所采用的工(gong)頻變壓(ya)器、濾波器的體積和重量(liang)都較大。調整管工(gong)作(zuo)在(zai)線性(xing)狀態，功耗大、效率低，需要(yao)加裝(zhuang)散熱器。