穩壓(ya)二極管工作在反向擊穿(chuan)狀態時，其兩端的電壓(ya)是基本(ben)不變的。利(li)用這一性質(zhi)，在電路里常用于構成穩壓(ya)電路。
穩(wen)壓二極管構成(cheng)的穩(wen)壓電路，雖然穩(wen)定(ding)度不很高，但卻具有簡單、經濟實(shi)用的優(you)點，因而應用非常廣(guang)泛。
在實際電路中，要(yao)使用(yong)好穩壓二極管，應注意如下(xia)幾個問題。
1、要注意(yi)一(yi)般二(er)(er)極管(guan)(guan)(guan)與(yu)穩(wen)(wen)壓二(er)(er)極管(guan)(guan)(guan)的(de)區(qu)別方法(fa)。不(bu)(bu)少的(de)一(yi)般二(er)(er)極管(guan)(guan)(guan)，特(te)別是(shi)(shi)玻璃封(feng)裝的(de)管(guan)(guan)(guan)，外形(xing)(xing)顏色等與(yu)穩(wen)(wen)壓二(er)(er)極管(guan)(guan)(guan)較相(xiang)似，如不(bu)(bu)細心區(qu)別，就會使用(yong)錯(cuo)誤。區(qu)別方法(fa)是(shi)(shi)：看(kan)外形(xing)(xing)，不(bu)(bu)少穩(wen)(wen)壓二(er)(er)極管(guan)(guan)(guan)為(wei)園(yuan)柱(zhu)形(xing)(xing)，較短粗，而一(yi)般二(er)(er)極管(guan)(guan)(guan)若為(wei)園(yuan)柱(zhu)形(xing)(xing)的(de)則較細長(chang)；看(kan)標(biao)志，穩(wen)(wen) 壓二(er)(er)極管(guan)(guan)(guan)的(de)外表(biao)面上都標(biao)有穩(wen)(wen)壓值(zhi)(zhi)(zhi)，如5V6，表(biao)示穩(wen)(wen)壓值(zhi)(zhi)(zhi)為(wei)5.6V；用(yong)萬用(yong)表(biao)進行(xing)測(ce)量，根據單向(xiang)導電性，用(yong)X1K擋先把被測(ce)二(er)(er)極管(guan)(guan)(guan)的(de)正負極性判(pan)斷(duan)出(chu)來，然(ran)后用(yong)X10K擋，黑表(biao)筆接(jie)二(er)(er)極管(guan)(guan)(guan)負極，紅表(biao)筆接(jie)二(er)(er)極管(guan)(guan)(guan)正極，測(ce)的(de)阻值(zhi)(zhi)(zhi)與(yu)X1K擋時相(xiang)比，若出(chu)現的(de)反向(xiang)阻值(zhi)(zhi)(zhi)很(hen)(hen)大，為(wei)一(yi)般二(er)(er)極管(guan)(guan)(guan)的(de)可(ke)能性很(hen)(hen)大，若出(chu)現的(de)反向(xiang)阻值(zhi)(zhi)(zhi)變得很(hen)(hen)小，則為(wei)穩(wen)(wen)壓二(er)(er)極管(guan)(guan)(guan)。
2、注意穩(wen)壓(ya)(ya)二(er)(er)(er)極管(guan)正(zheng)(zheng)(zheng)向使(shi)(shi)用(yong)(yong)(yong)(yong)與(yu)反向使(shi)(shi)用(yong)(yong)(yong)(yong)的(de)區別。穩(wen)壓(ya)(ya)二(er)(er)(er)極管(guan)正(zheng)(zheng)(zheng)向導(dao)通使(shi)(shi)用(yong)(yong)(yong)(yong)時(shi)(shi)，與(yu)一(yi)般(ban)二(er)(er)(er)極管(guan)正(zheng)(zheng)(zheng)向導(dao)通使(shi)(shi)用(yong)(yong)(yong)(yong)時(shi)(shi)基本相同(tong)，正(zheng)(zheng)(zheng)向導(dao)通后兩端(duan)電(dian)壓(ya)(ya)也是(shi)基本不變(bian)的(de)，都(dou)約為0.7V。從理論上講，穩(wen)壓(ya)(ya)二(er)(er)(er)極管(guan)也可(ke)正(zheng)(zheng)(zheng)向使(shi)(shi)用(yong)(yong)(yong)(yong)做穩(wen)壓(ya)(ya)管(guan)用(yong)(yong)(yong)(yong)，但其穩(wen)壓(ya)(ya)值將低于1V，且穩(wen)壓(ya)(ya)性(xing)能也不好(hao)，一(yi)般(ban)不單獨用(yong)(yong)(yong)(yong)穩(wen)壓(ya)(ya)管(guan)的(de)正(zheng)(zheng)(zheng)向導(dao)通特性(xing)來穩(wen)壓(ya)(ya)，而是(shi)用(yong)(yong)(yong)(yong)反向擊穿特性(xing)來穩(wen)壓(ya)(ya)。反向擊穿電(dian)壓(ya)(ya)值即為穩(wen)壓(ya)(ya)值。有時(shi)(shi)將兩個穩(wen)壓(ya)(ya)管(guan)串聯使(shi)(shi)用(yong)(yong)(yong)(yong)，一(yi)個利(li)用(yong)(yong)(yong)(yong)它的(de)正(zheng)(zheng)(zheng)向特性(xing)，另一(yi)個利(li)用(yong)(yong)(yong)(yong)它的(de)反向特性(xing)，則既能穩(wen)壓(ya)(ya)又可(ke)起溫(wen)度補償(chang)作用(yong)(yong)(yong)(yong)，以提(ti)高穩(wen)壓(ya)(ya)效果。
3、要(yao)(yao)注意限(xian)(xian)流(liu)電(dian)(dian)(dian)(dian)阻的(de)作用及阻值(zhi)大小的(de)影響。在穩(wen)壓(ya)(ya)(ya)二(er)極(ji)(ji)管(guan)穩(wen)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)路中，一般都(dou)要(yao)(yao)串接一個(ge)電(dian)(dian)(dian)(dian)阻R，如圖1或2示。該電(dian)(dian)(dian)(dian)阻在電(dian)(dian)(dian)(dian)路中起(qi)限(xian)(xian)流(liu)和(he)提(ti)高穩(wen)壓(ya)(ya)(ya)效(xiao)(xiao)果的(de)作用。若不加該電(dian)(dian)(dian)(dian)阻即當R=0時，容(rong)易(yi)燒壞穩(wen)壓(ya)(ya)(ya)管(guan)，穩(wen)壓(ya)(ya)(ya)效(xiao)(xiao)果也(ye)會極(ji)(ji)差(cha)。限(xian)(xian)流(liu)電(dian)(dian)(dian)(dian)阻的(de)阻值(zhi)越(yue)(yue)大，電(dian)(dian)(dian)(dian)路穩(wen)壓(ya)(ya)(ya)性(xing)能越(yue)(yue)好，但輸入與輸出壓(ya)(ya)(ya)差(cha)也(ye)會過大，耗(hao)電(dian)(dian)(dian)(dian)也(ye)就越(yue)(yue)多。
4、要注意輸入與輸出(chu)的(de)壓(ya)(ya)差(cha)。正(zheng)常使用時(shi)，穩(wen)壓(ya)(ya)二極管(guan)穩(wen)壓(ya)(ya)電(dian)路的(de)輸出(chu)電(dian)壓(ya)(ya)等于(yu)穩(wen)壓(ya)(ya)管(guan)反向擊穿后兩端的(de)穩(wen)壓(ya)(ya)值(zhi)，若輸入到穩(wen)壓(ya)(ya)電(dian)路中的(de)電(dian)壓(ya)(ya)值(zhi)小于(yu)穩(wen)壓(ya)(ya)管(guan)的(de)穩(wen)壓(ya)(ya)值(zhi)，則電(dian)路將失(shi)去穩(wen)壓(ya)(ya)作用，只有(you)是大(da)于(yu)關系時(shi)，才(cai)有(you)穩(wen)壓(ya)(ya)作用，并且壓(ya)(ya)差(cha)越大(da)，限流電(dian)阻的(de)阻值(zhi)也應越大(da)，否則會損(sun)壞穩(wen)壓(ya)(ya)管(guan)。
5、穩(wen)壓(ya)(ya)管(guan)(guan)可串(chuan)(chuan)聯(lian)(lian)使(shi)用(yong)。幾(ji)個(ge)穩(wen)壓(ya)(ya)管(guan)(guan)串(chuan)(chuan)聯(lian)(lian)后(hou)(hou)，可獲得(de)多個(ge)不同(tong)(tong)的穩(wen)壓(ya)(ya)值(zhi)，故串(chuan)(chuan)聯(lian)(lian)使(shi)用(yong)較常(chang)見(jian)。下面舉例(li)說明兩個(ge)穩(wen)壓(ya)(ya)管(guan)(guan)串(chuan)(chuan)聯(lian)(lian)使(shi)用(yong)后(hou)(hou)，如(ru)何(he)求得(de)穩(wen)壓(ya)(ya)值(zhi)。若一個(ge)穩(wen)壓(ya)(ya)管(guan)(guan)的穩(wen)壓(ya)(ya)值(zhi)為(wei)(wei)5.6V，另一個(ge)穩(wen)壓(ya)(ya)值(zhi)為(wei)(wei)3.6V，設穩(wen)壓(ya)(ya)管(guan)(guan)正(zheng)向導通(tong)時電壓(ya)(ya)均為(wei)(wei)0.7V，則串(chuan)(chuan)聯(lian)(lian)后(hou)(hou)共有四種不同(tong)(tong)的穩(wen)壓(ya)(ya)值(zhi)，如(ru)圖1示。
6、穩(wen)(wen)壓(ya)(ya)管一般不并(bing)聯(lian)使用。幾(ji)個穩(wen)(wen)壓(ya)(ya)管并(bing)聯(lian)后，穩(wen)(wen)壓(ya)(ya)值將(jiang)由最低(包括正向(xiang)導通后的(de)電壓(ya)(ya)值)的(de)一個來(lai)決定。還是以上(shang)述兩個穩(wen)(wen)壓(ya)(ya)管為例，來(lai)說明穩(wen)(wen)壓(ya)(ya)值的(de)計算方法(fa)。兩個并(bing)聯(lian)后共有四種情(qing)況，穩(wen)(wen)壓(ya)(ya)值只有兩個。除(chu)非特殊(shu)情(qing)況，穩(wen)(wen)壓(ya)(ya)二極管都不并(bing)聯(lian)使用。
