實踐證明(ming)，即使(shi)電路(lu)原(yuan)理圖設(she)計正確，印(yin)制(zhi)電路(lu)板(ban)設(she)計不當(dang)，也會對電子設(she)備(bei)的可靠性產(chan)生不利(li)影(ying)響(xiang)。例如，如果(guo)印(yin)制(zhi)板(ban)兩條細平行線靠得很近，則會形(xing)成(cheng)信號(hao)波形(xing)的延遲(chi)，在傳輸線的終端形(xing)成(cheng)反射噪聲。那么電(dian)源(yuan)適配(pei)器(qi)如(ru)何進行(xing)合理(li)的元器件布(bu)局呢？

在設計印制電(dian)路(lu)板的(de)時候，應注意采用(yong)正(zheng)確的(de)方法。每一個(ge)開關(guan)電(dian)源(yuan)都有四個(ge)電(dian)流回(hui)路(lu)：

（1）電源開(kai)關交流(liu)回路(lu)

（2）輸出整流(liu)交(jiao)流(liu)回路(lu)

（3）輸(shu)入信號(hao)源電流回路

（4）輸出負載電流(liu)回路輸入回路

通過一個近似直流(liu)的(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)對(dui)輸(shu)(shu)入電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)充電(dian)(dian)(dian)(dian)(dian)，濾波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)主(zhu)要起(qi)到一個寬帶儲(chu)能(neng)作用(yong)；類似地，輸(shu)(shu)出(chu)濾波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)也用(yong)來儲(chu)存來自輸(shu)(shu)出(chu)整流(liu)器的(de)(de)高頻(pin)能(neng)量(liang)，同時消除(chu)輸(shu)(shu)出(chu)負(fu)載回(hui)路的(de)(de)直流(liu)能(neng)量(liang)。所(suo)以，輸(shu)(shu)入和輸(shu)(shu)出(chu)濾波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)(de)接(jie)線端(duan)十分重要，輸(shu)(shu)入及(ji)輸(shu)(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)流(liu)回(hui)路應分別只從(cong)濾波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)(de)接(jie)線端(duan)連(lian)接(jie)到電(dian)(dian)(dian)(dian)(dian)源；如果在輸(shu)(shu)入/輸(shu)(shu)出(chu)回(hui)路和電(dian)(dian)(dian)(dian)(dian)源開(kai)關/整流(liu)回(hui)路之間的(de)(de)連(lian)接(jie)無法與(yu)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)(de)接(jie)線端(duan)直接(jie)相連(lian)，交流(liu)能(neng)量(liang)將由(you)輸(shu)(shu)入或輸(shu)(shu)出(chu)濾波(bo)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)并輻射到環境中去。

電源開關(guan)交流(liu)回(hui)(hui)路(lu)和整流(liu)器的交流(liu)回(hui)(hui)路(lu)包(bao)含高幅(fu)梯形電流(liu)，這些電流(liu)中諧波成分(fen)很高，其頻率(lv)遠大于開關(guan)基頻，峰值幅(fu)度(du)可(ke)高達(da)持續輸入/輸出直流(liu)電流(liu)幅(fu)度(du)的5倍，過渡時間通(tong)常約為50ns。這兩個回(hui)(hui)路(lu)最容(rong)易產生電磁干擾，因此(ci)必須在(zai)電源中其它印制(zhi)線布線之前(qian)先布好這些交流(liu)回(hui)(hui)路(lu)，每個回(hui)(hui)路(lu)的三種主要的元件濾波電容(rong)、電源開關(guan)或整流(liu)器、電感或變壓(ya)器應(ying)彼此(ci)相鄰地進行(xing)放(fang)置(zhi)，調整元件位置(zhi)使它們之間的電流(liu)路(lu)徑盡可(ke)能短。