開關電源不同于線性電源適配器，前者調(diao)整(zheng)管(guan)工作(zuo)(zuo)在(zai)通(tong)(tong)、斷(duan)狀態(tai)，后者調(diao)整(zheng)管(guan)工作(zuo)(zuo)在(zai)線性狀態(tai)。電(dian)(dian)(dian)源(yuan)適(shi)配(pei)(pei)器(qi)通(tong)(tong)過控制調(diao)整(zheng)管(guan)的通(tong)(tong)、斷(duan)時間實現穩壓。電(dian)(dian)(dian)源(yuan)適(shi)配(pei)(pei)器(qi)的優點是體積(ji)小(xiao)(xiao)、重量輕、功耗(hao)小(xiao)(xiao)、穩壓范圍寬，效率(lv)可高達80%～90%。調(diao)整(zheng)管(guan)功率(lv)損耗(hao)小(xiao)(xiao)，散熱器(qi)也隨之減小(xiao)(xiao)。英(ying)規電(dian)(dian)(dian)源(yuan)適(shi)配(pei)(pei)器(qi)工作(zuo)(zuo)頻率(lv)在(zai)幾十(shi)千赫茲甚至幾百千赫茲，濾波(bo)電(dian)(dian)(dian)感、電(dian)(dian)(dian)容(rong)元(yuan)件(jian)可用較(jiao)小(xiao)(xiao)的容(rong)量，允許的環境(jing)溫度也可以大(da)大(da)提高，廣(guang)泛應用在(zai)各種電(dian)(dian)(dian)子設(she)備中。本(ben)章主(zhu)要(yao)介紹電(dian)(dian)(dian)源(yuan)適(shi)配(pei)(pei)器(qi)的基本(ben)構成、分類(lei)及工作(zuo)(zuo)原理，讓讀者對(dui)電(dian)(dian)(dian)源(yuan)適(shi)配(pei)(pei)器(qi)有一(yi)個初步的認(ren)識。

　　穩壓電源適配器的比較

　　電(dian)(dian)子設(she)(she)備離不開(kai)電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)。電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)供給電(dian)(dian)子設(she)(she)備所需要(yao)的(de)能量。電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)的(de)性能、質(zhi)量直接影響著(zhu)電(dian)(dian)子設(she)(she)備的(de)安全(quan)可靠(kao)運(yun)行，故此對電(dian)(dian)子設(she)(she)備電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)性能、質(zhi)量的(de)要(yao)求也越來越高。現有的(de)電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)主要(yao)有兩大類：串聯線性穩壓(ya)電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)(簡稱線性電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi))和開(kai)關穩壓(ya)電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi)(簡稱電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(qi))。這兩類電(dian)(dian)源(yuan)(yuan)(yuan)適(shi)(shi)(shi)(shi)配(pei)(pei)(pei)(pei)器(qi)(qi)(qi)(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

　　線性(xing)電(dian)源適配器通常都(dou)是由電(dian)網所提供的交流電(dian)，經過變壓(ya)、整(zheng)流、濾波(bo)和穩壓(ya)環節而得到。其各個部分電(dian)路(lu)的作用如下：

　　①電源適配器(qi)變壓(ya)器(qi)——將220V電網電壓(ya)轉換為整流(liu)電路所需(xu)要的交流(liu)電壓(ya)值，而少部分電路采用電容降壓(ya)，如遙控電風扇電路。

　　②整(zheng)(zheng)流(liu)(liu)(liu)電(dian)路——將交流(liu)(liu)(liu)電(dian)壓轉換為脈動直流(liu)(liu)(liu)電(dian)壓。常(chang)用的整(zheng)(zheng)流(liu)(liu)(liu)電(dian)路有(you)半(ban)波(bo)整(zheng)(zheng)流(liu)(liu)(liu)電(dian)路、全波(bo)整(zheng)(zheng)流(liu)(liu)(liu)電(dian)路和橋式整(zheng)(zheng)流(liu)(liu)(liu)電(dian)路。

　　③濾(lv)波(bo)(bo)電(dian)(dian)路(lu)——將脈動直(zhi)流(liu)電(dian)(dian)壓轉換成較為平滑的(de)直(zhi)流(liu)電(dian)(dian)壓。線性電(dian)(dian)源(yuan)適配(pei)器中(zhong)常用的(de)濾(lv)波(bo)(bo)電(dian)(dian)路(lu)有電(dian)(dian)感濾(lv)波(bo)(bo)、電(dian)(dian)容濾(lv)波(bo)(bo)和阻(zu)容濾(lv)波(bo)(bo)，其中(zhong)最常用的(de)是電(dian)(dian)容濾(lv)波(bo)(bo)。

　　④穩(wen)(wen)(wen)壓(ya)電(dian)路(lu)(lu)——將直流電(dian)源適(shi)配器的輸(shu)出電(dian)壓(ya)穩(wen)(wen)(wen)定，基本不受電(dian)網電(dian)壓(ya)或負(fu)載的影(ying)響。在線性電(dian)源適(shi)配器中常用(yong)的穩(wen)(wen)(wen)壓(ya)電(dian)路(lu)(lu)有二極管穩(wen)(wen)(wen)壓(ya)、串聯穩(wen)(wen)(wen)壓(ya)。其中，串聯穩(wen)(wen)(wen)壓(ya)有現成(cheng)的集成(cheng)電(dian)路(lu)(lu)，如固定電(dian)壓(ya)輸(shu)出的集成(cheng)電(dian)路(lu)(lu)有LM78××，LM79××等(deng)，可調電(dian)壓(ya)輸(shu)出的集成(cheng)電(dian)路(lu)(lu)有LM317和(he)LM337等(deng)。

　　4個功能模塊的線性穩壓電源適配器

　　線性電(dian)源(yuan)適配器的(de)優點是穩定性好、瞬(shun)態響應速(su)度快、可靠性高、輸出(chu)電(dian)壓(ya)精度高和(he)輸出(chu)紋波電(dian)壓(ya)小;缺點是工(gong)(gong)作頻率低，所采用的(de)工(gong)(gong)頻變壓(ya)器、濾波器的(de)體積和(he)重量(liang)都較大。調整(zheng)管(guan)工(gong)(gong)作在線性狀態，功(gong)耗大、效率低，需要加裝散熱器。