在進(jin)行電(dian)器電(dian)路(lu)模塊規(gui)劃或給(gei)新(xin)產品定型時，許多(duo)人不會去細心考慮(lv)配套(tao)開關(guan)電(dian)源的選擇，直到發現開關(guan)電(dian)源部分(fen)有了故(gu)障問題，才從頭處(chu)理這個問題。

一(yi)、選擇開關電(dian)源的基本依據

電(dian)壓和電(dian)流(liu)規(gui)劃(hua)，這是兩個(ge)最(zui)容易承認的(de)目標，只需依據電(dian)路的(de)功耗(hao)計(ji)算(suan)出即可。也應考慮檢驗高、低供電(dian)電(dian)壓極值。

大多數固(gu)定電源答應輸(shu)出(chu)電壓±10%的規(gui)(gui)劃內改動(dong)，假(jia)設(she)這還(huan)不能(neng)滿意電路要(yao)求(qiu)，可選用輸(shu)出(chu)可調(diao)的或答應**改動(dong)規(gui)(gui)劃的電源。

假設(she)(she)用該(gai)電(dian)源(yuan)給組合式設(she)(she)備(bei)供電(dian)，則設(she)(she)備(bei)所需**的(de)電(dian)流的(de)75%到90%由(you)一個(ge)電(dian)源(yuan)供應，不夠(gou)部分可并接兩個(ge)或更多電(dian)源(yuan)。

二、開關電源(yuan)的(de)擴展和安全性

1、并聯或串聯作業

當一(yi)個電(dian)源(yuan)(yuan)不能滿(man)意所(suo)需的(de)電(dian)壓或(huo)電(dian)流規劃時，可將兩個或(huo)多個電(dian)源(yuan)(yuan)(或(huo)將同(tong)一(yi)電(dian)源(yuan)(yuan)的(de)不同(tong)輸出)并聯(lian)(lian)(lian)或(huo)串聯(lian)(lian)(lian)起來(lai)運用(yong)。在(zai)這種作業(ye)方式下，各電(dian)源(yuan)(yuan)模(mo)塊間的(de)穩(wen)壓和控(kong)制電(dian)路之(zhi)間的(de)聯(lian)(lian)(lian)絡仍然(ran)存在(zai)，只不過一(yi)個電(dian)源(yuan)(yuan)作為(wei)主控(kong)方另一(yi)個電(dian)源(yuan)(yuan)作為(wei)受控(kong)方運用(yong)。

2、過載保護

因為一個電(dian)(dian)源要供應不同的電(dian)(dian)路運(yun)用(yong)，這些電(dian)(dian)路的電(dian)(dian)流的流量可(ke)能是不知道的，為了(le)防止對電(dian)(dian)源的損壞(huai)，需設置保護電(dian)(dian)路的規劃。

簡直一(yi)切的(de)(de)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)都具有以下特征：在(zai)超出輸出規(gui)(gui)劃時，要(yao)么輸出保持在(zai)**輸出值，要(yao)么就自行封閉電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)。某(mou)些程控電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)除可(ke)用(yong)程序設(she)定輸出規(gui)(gui)劃外(wai)，還能(neng)主(zhu)動(dong)設(she)置(zhi)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)安穩(wen)輸出的(de)(de)類型。也就是說，當外(wai)電(dian)(dian)(dian)(dian)(dian)路需求的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓或電(dian)(dian)(dian)(dian)(dian)流(liu)超越設(she)置(zhi)極限時，電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)可(ke)主(zhu)動(dong)地由(you)恒壓源(yuan)(yuan)(yuan)(yuan)(yuan)變(bian)成恒流(liu)源(yuan)(yuan)(yuan)(yuan)(yuan)或由(you)值流(liu)源(yuan)(yuan)(yuan)(yuan)(yuan)變(bian)成恒壓源(yuan)(yuan)(yuan)(yuan)(yuan)。為電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)加(jia)上保護二極管能(neng)夠(gou)防(fang)止誤接外(wai)接電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)的(de)(de)極性構成的(de)(de)損壞(huai)。熱傳(chuan)感器也可(ke)用(yong)于防(fang)止由(you)于電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)繼續(xu)作業在(zai)過載狀態或冷(leng)卻無效而燒壞(huai)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)(yuan)。

三、開關電源內部潛在的構成損(sun)害的根源

1、脈動與噪聲

志向(xiang)的(de)直流電(dian)(dian)源(yuan)(yuan)應(ying)供應(ying)純真的(de)直流，然(ran)而總有一(yi)些煩(fan)擾存在，比如在開關(guan)電(dian)(dian)源(yuan)(yuan)輸出端口疊加(jia)的(de)脈動電(dian)(dian)流和(he)高頻振動。這兩種煩(fan)擾再加(jia)上(shang)電(dian)(dian)源(yuan)(yuan)自身發(fa)生的(de)尖峰(feng)噪聲使電(dian)(dian)源(yuan)(yuan)出現(xian)斷續和(he)隨意的(de)漂移。

2、安穩度

當(dang)線電(dian)壓(ya)或負載電(dian)流改動肘(zhou)，直流電(dian)源的(de)輸出(chu)電(dian)壓(ya)也會(hui)有(you)所高低。穩(wen)壓(ya)程度由(you)穩(wen)壓(ya)電(dian)路的(de)參數(shu)抉擇(ze)，參數(shu)是指濾波電(dian)容的(de)容量和能量開釋(shi)的(de)速率。

假設給電(dian)源(yuan)供電(dian)的一個相對安穩的電(dian)源(yuan)，那么只需基本(ben)的負載穩壓。安穩度的大小一般定義為空(kong)載或(huo)滿載時輸出(chu)電(dian)壓的百(bai)分比，或(huo)電(dian)壓的改(gai)動(dong)值。

3、內部阻抗

相(xiang)對(dui)(dui)(dui)較大的電源內阻對(dui)(dui)(dui)負載來講有兩點(dian)倒霉，首先是倒霉于負載穩壓電路作業，更(geng)為倒霉的是負載電流(liu)的任何改動都會導致(zhi)直流(liu)電源輸出的高低，這(zhe)種高低對(dui)(dui)(dui)檢驗效(xiao)果的影(ying)響同脈沖與噪聲對(dui)(dui)(dui)檢驗效(xiao)果構成的影(ying)響完(wan)全相(xiang)同。

4、開關電源(yuan)瞬態呼應(ying)或恢復

電(dian)源瞬(shun)態呼(hu)應和(he)恢(hui)(hui)復時(shi)(shi)間(jian)的(de)(de)(de)(de)大小標明輸(shu)出負(fu)(fu)載(zai)遽然改動(dong)(dong)(dong)時(shi)(shi)，電(dian)源穩(wen)壓(ya)電(dian)路恢(hui)(hui)復正常(chang)電(dian)壓(ya)能力(li)的(de)(de)(de)(de)大小。有(you)兩種參(can)數來標定(ding)電(dian)源瞬(shun)態呼(hu)應和(he)恢(hui)(hui)復：一(yi)是(shi)當(dang)負(fu)(fu)載(zai)遽然發(fa)生改動(dong)(dong)(dong)時(shi)(shi)輸(shu)出的(de)(de)(de)(de)違反值(zhi)；二(er)是(shi)輸(shu)出恢(hui)(hui)復到(dao)原本值(zhi)所(suo)用(yong)(yong)的(de)(de)(de)(de)時(shi)(shi)間(jian)。為共同(tong)起見(jian)，一(yi)般(ban)在(zai)負(fu)(fu)載(zai)改動(dong)(dong)(dong)10%時(shi)(shi)，用(yong)(yong)輸(shu)出違反峰值(zhi)電(dian)壓(ya)的(de)(de)(de)(de)毫優數標定(ding)輸(shu)出違反量，用(yong)(yong)輸(shu)出恢(hui)(hui)復到(dao)正常(chang)值(zhi)所(suo)用(yong)(yong)毫伏(fu)數標定(ding)恢(hui)(hui)復時(shi)(shi)間(jian)。還有(you)一(yi)些生產(chan)廠商，用(yong)(yong)**的(de)(de)(de)(de)負(fu)(fu)載(zai)電(dian)流(liu)(liu)改動(dong)(dong)(dong)測定(ding)恢(hui)(hui)復時(shi)(shi)間(jian)。比如(ru)用(yong)(yong)輸(shu)出電(dian)流(liu)(liu)改動(dong)(dong)(dong)的(de)(de)(de)(de)50%到(dao)****時(shi)(shi)所(suo)用(yong)(yong)的(de)(de)(de)(de)恢(hui)(hui)復正常(chang)值(zhi)的(de)(de)(de)(de)時(shi)(shi)間(jian)。