一、電源模塊常見異常有哪些

1、輸入電壓過高

電(dian)源模塊(kuai)輸(shu)入電(dian)壓過(guo)高，輕則導致系統無法(fa)正(zheng)常工作，重(zhong)則燒毀電(dian)路。

2、輸出電壓過低

電源模塊輸(shu)出電(dian)(dian)壓(ya)過低(di)，可能(neng)會(hui)導(dao)致整體系統不能(neng)正常工作(zuo)(zuo)，如微控制器系統中，負載突然增大(da)，會(hui)拉低(di)微控制器供電(dian)(dian)電(dian)(dian)壓(ya)，容(rong)易造成復位(wei)。并(bing)且電(dian)(dian)源長時(shi)間低(di)電(dian)(dian)壓(ya)工作(zuo)(zuo)，電(dian)(dian)路的(de)(de)壽命會(hui)出現(xian)極大(da)的(de)(de)折損。

3、輸出紋波噪聲過大

輸出紋波噪聲(sheng)(sheng)過(guo)(guo)大的原因：電(dian)(dian)(dian)源模塊與主(zhu)電(dian)(dian)(dian)路噪聲(sheng)(sheng)敏(min)感(gan)元件(jian)距離過(guo)(guo)近、主(zhu)電(dian)(dian)(dian)路噪聲(sheng)(sheng)敏(min)感(gan)元件(jian)的電(dian)(dian)(dian)源輸入端處未(wei)接去耦電(dian)(dian)(dian)等(deng)。

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4、電源耐壓不良

電(dian)源模塊的耐(nai)壓值(zhi)一(yi)般高達幾千伏，不過在應用或者測試中可(ke)能會(hui)出現達不到指標的情況。

二、電源模塊維修教程

1、無輸出，保險管正常。這種現象(xiang)說明(ming)開關電(dian)(dian)(dian)(dian)源未工作或(huo)進入了(le)保護狀(zhuang)態。首先要測量電(dian)(dian)(dian)(dian)源控(kong)制(zhi)芯(xin)片(pian)(pian)的(de)啟(qi)動(dong)腳(jiao)是否(fou)有啟(qi)動(dong)電(dian)(dian)(dian)(dian)壓(ya)，若(ruo)無(wu)(wu)啟(qi)動(dong)電(dian)(dian)(dian)(dian)壓(ya)或(huo)者啟(qi)動(dong)電(dian)(dian)(dian)(dian)壓(ya)太低，則要檢查啟(qi)動(dong)電(dian)(dian)(dian)(dian)阻和啟(qi)動(dong)腳(jiao)外接的(de)元件(jian)是否(fou)漏電(dian)(dian)(dian)(dian)，此時如(ru)電(dian)(dian)(dian)(dian)源控(kong)制(zhi)芯(xin)片(pian)(pian)正(zheng)常，則經(jing)上述檢查可以迅速查到故障。若(ruo)有啟(qi)動(dong)電(dian)(dian)(dian)(dian)壓(ya)，則測量控(kong)制(zhi)芯(xin)片(pian)(pian)的(de)輸(shu)出端在(zai)開機(ji)瞬(shun)間是否(fou)有高、低電(dian)(dian)(dian)(dian)平的(de)跳(tiao)變(bian)，若(ruo)無(wu)(wu)跳(tiao)變(bian)，說明(ming)控(kong)制(zhi)芯(xin)片(pian)(pian)壞、外圍(wei)振蕩電(dian)(dian)(dian)(dian)路元件(jian)或(huo)保護電(dian)(dian)(dian)(dian)路有問題，可先代換控(kong)制(zhi)芯(xin)片(pian)(pian)，再檢查外圍(wei)元件(jian);若(ruo)有跳(tiao)變(bian)，一般為開關管不良或(huo)損壞。

2、保險燒或炸。主要檢(jian)查300V上的大濾波電(dian)容、整流橋(qiao)各(ge)二極(ji)管(guan)(guan)及(ji)開(kai)關管(guan)(guan)等部位，抗(kang)干(gan)擾(rao)電(dian)路出問題也會導致(zhi)保險(xian)燒、發黑。需要注意的是：因開(kai)關管(guan)(guan)擊穿導致(zhi)保險(xian)燒一(yi)般會把電(dian)流檢(jian)測電(dian)阻(zu)和(he)電(dian)源控制芯片燒壞。負溫度系數熱(re)敏電(dian)阻(zu)也很容易和(he)保險(xian)一(yi)起(qi)被燒壞。

3、有輸出電壓，但輸出電壓過高。這種故障一(yi)般來自于穩壓取(qu)樣(yang)和穩壓控制(zhi)電(dian)(dian)路。在(zai)直(zhi)流輸出、取(qu)樣(yang)電(dian)(dian)阻、誤差取(qu)樣(yang)放大(da)器如(ru)TL431、光耦、電(dian)(dian)源(yuan)控制(zhi)芯(xin)片等電(dian)(dian)路共同構成一(yi)個閉合的(de)控制(zhi)環路，任何(he)一(yi)處(chu)出問(wen)題(ti)就會導致(zhi)輸出電(dian)(dian)壓升高。

4、輸出電壓過低。除穩壓(ya)控制電路(lu)會(hui)(hui)引起輸出電壓(ya)低(di)(di)，還有下面一些原(yuan)因也(ye)會(hui)(hui)引起輸出電壓(ya)低(di)(di)：

（1）輸出電(dian)壓端整(zheng)流二極(ji)管、濾(lv)波電(dian)容失(shi)效等，可以通過(guo)代(dai)換法進(jin)行判(pan)斷。

（2）開(kai)關管的性(xing)能下(xia)降，必(bi)然(ran)導致開(kai)關管不能正(zheng)常(chang)導通，使電源的內阻增加，帶(dai)負載能力下(xia)降。