開關電源不同于線性電源適配器，前者(zhe)調(diao)整(zheng)管(guan)(guan)工(gong)(gong)作(zuo)在(zai)(zai)通(tong)(tong)、斷(duan)狀態，后者(zhe)調(diao)整(zheng)管(guan)(guan)工(gong)(gong)作(zuo)在(zai)(zai)線性狀態。電(dian)源(yuan)(yuan)適配(pei)器(qi)(qi)(qi)(qi)通(tong)(tong)過控制調(diao)整(zheng)管(guan)(guan)的(de)(de)(de)通(tong)(tong)、斷(duan)時間(jian)實現(xian)穩壓。電(dian)源(yuan)(yuan)適配(pei)器(qi)(qi)(qi)(qi)的(de)(de)(de)優點(dian)是體積小、重(zhong)量輕、功耗(hao)小、穩壓范圍寬(kuan)，效率(lv)可(ke)高達80%～90%。調(diao)整(zheng)管(guan)(guan)功率(lv)損(sun)耗(hao)小，散熱(re)器(qi)(qi)(qi)(qi)也隨之減小。英規電(dian)源(yuan)(yuan)適配(pei)器(qi)(qi)(qi)(qi)工(gong)(gong)作(zuo)頻(pin)率(lv)在(zai)(zai)幾(ji)十千赫(he)茲(zi)甚(shen)至幾(ji)百千赫(he)茲(zi)，濾波電(dian)感、電(dian)容元件(jian)可(ke)用較(jiao)小的(de)(de)(de)容量，允許的(de)(de)(de)環(huan)境溫度也可(ke)以(yi)大大提(ti)高，廣泛應用在(zai)(zai)各種電(dian)子設備中。本章主(zhu)要介紹(shao)電(dian)源(yuan)(yuan)適配(pei)器(qi)(qi)(qi)(qi)的(de)(de)(de)基本構成(cheng)、分類及工(gong)(gong)作(zuo)原理(li)，讓(rang)讀者(zhe)對電(dian)源(yuan)(yuan)適配(pei)器(qi)(qi)(qi)(qi)有一個初(chu)步的(de)(de)(de)認識。

　　穩壓電源適配器的比較

　　電(dian)(dian)(dian)(dian)(dian)子(zi)設備(bei)(bei)離(li)不開電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)。電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)供(gong)給電(dian)(dian)(dian)(dian)(dian)子(zi)設備(bei)(bei)所需要(yao)的(de)能量(liang)。電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)的(de)性能、質量(liang)直(zhi)接影響著(zhu)電(dian)(dian)(dian)(dian)(dian)子(zi)設備(bei)(bei)的(de)安全可靠運(yun)行，故此對電(dian)(dian)(dian)(dian)(dian)子(zi)設備(bei)(bei)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)性能、質量(liang)的(de)要(yao)求也(ye)越(yue)來越(yue)高。現有(you)的(de)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)主要(yao)有(you)兩大類：串聯線性穩(wen)壓(ya)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)(簡稱(cheng)線性電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi))和開關穩(wen)壓(ya)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)(簡稱(cheng)電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi))。這兩類電(dian)(dian)(dian)(dian)(dian)源(yuan)適(shi)(shi)配(pei)器(qi)各具特色而被廣泛應用。

　　線性電源適配器的結構與特點

　　線性(xing)電(dian)源適配器通常都是由電(dian)網(wang)所提供(gong)的(de)交流電(dian)，經(jing)過變壓(ya)(ya)、整流、濾波和(he)穩(wen)壓(ya)(ya)環(huan)節而得到。其各個部(bu)分電(dian)路(lu)的(de)作(zuo)用如下：

　　①電(dian)(dian)(dian)源適配器(qi)變壓器(qi)——將220V電(dian)(dian)(dian)網電(dian)(dian)(dian)壓轉換(huan)為整流電(dian)(dian)(dian)路(lu)所需要的(de)交流電(dian)(dian)(dian)壓值，而(er)少(shao)部分電(dian)(dian)(dian)路(lu)采用電(dian)(dian)(dian)容(rong)降壓，如遙控(kong)電(dian)(dian)(dian)風(feng)扇電(dian)(dian)(dian)路(lu)。

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

　　③濾(lv)波電(dian)(dian)路——將脈動直流電(dian)(dian)壓轉換成較為平滑的直流電(dian)(dian)壓。線性電(dian)(dian)源適配器(qi)中常(chang)用(yong)的濾(lv)波電(dian)(dian)路有電(dian)(dian)感濾(lv)波、電(dian)(dian)容濾(lv)波和阻容濾(lv)波，其中最(zui)常(chang)用(yong)的是電(dian)(dian)容濾(lv)波。

　　④穩(wen)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)——將(jiang)直(zhi)流電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)配器(qi)的(de)輸(shu)出電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)穩(wen)定(ding)，基(ji)本不受(shou)電(dian)(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)或負載的(de)影響。在線性電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)適(shi)配器(qi)中常用的(de)穩(wen)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)有(you)二極管穩(wen)壓(ya)(ya)、串(chuan)(chuan)聯(lian)穩(wen)壓(ya)(ya)。其中，串(chuan)(chuan)聯(lian)穩(wen)壓(ya)(ya)有(you)現成的(de)集(ji)成電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)，如固(gu)定(ding)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)輸(shu)出的(de)集(ji)成電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)有(you)LM78××，LM79××等(deng)，可調(diao)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)輸(shu)出的(de)集(ji)成電(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)有(you)LM317和LM337等(deng)。

　　4個功能模塊的線性穩壓電源適配器

　　線性電(dian)(dian)源適(shi)配器(qi)的優點(dian)是(shi)穩定性好、瞬態響(xiang)應速度(du)(du)快、可靠(kao)性高、輸出電(dian)(dian)壓精度(du)(du)高和(he)輸出紋波(bo)電(dian)(dian)壓小;缺點(dian)是(shi)工(gong)作(zuo)頻(pin)率低(di)，所(suo)采用的工(gong)頻(pin)變壓器(qi)、濾波(bo)器(qi)的體(ti)積和(he)重量(liang)都較大。調整管(guan)工(gong)作(zuo)在(zai)線性狀態，功耗大、效(xiao)率低(di)，需要加裝散熱器(qi)。