穩壓二極管工作在反向擊穿狀態時，其兩端的(de)電壓是(shi)基本不變的(de)。利用(yong)這一(yi)性質(zhi)，在電路里(li)常用(yong)于構成穩壓電路。
穩壓二極管構成的(de)穩壓電路(lu)，雖然(ran)穩定度不(bu)很高，但卻(que)具(ju)有簡單、經(jing)濟(ji)實用(yong)的(de)優(you)點，因而應用(yong)非(fei)常廣泛(fan)。
在實(shi)際電路中(zhong)，要使(shi)用好穩壓二極管，應注意如(ru)下幾個問(wen)題。
1、要注意(yi)一(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)管與穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)管的(de)區(qu)(qu)別方法(fa)。不少(shao)(shao)的(de)一(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)管，特別是(shi)玻璃(li)封裝的(de)管，外(wai)(wai)形顏色(se)等與穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)管較(jiao)相似(si)，如不細心區(qu)(qu)別，就會使用錯誤(wu)。區(qu)(qu)別方法(fa)是(shi)：看外(wai)(wai)形，不少(shao)(shao)穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)管為(wei)園柱(zhu)形，較(jiao)短(duan)粗，而一(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)管若(ruo)為(wei)園柱(zhu)形的(de)則(ze)較(jiao)細長；看標志(zhi)，穩(wen)(wen)(wen) 壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)管的(de)外(wai)(wai)表(biao)面上都標有穩(wen)(wen)(wen)壓(ya)值，如5V6，表(biao)示穩(wen)(wen)(wen)壓(ya)值為(wei)5.6V；用萬用表(biao)進行(xing)測量，根據單向導電性(xing)(xing)(xing)，用X1K擋先把被測二(er)(er)(er)極(ji)(ji)(ji)(ji)管的(de)正負(fu)極(ji)(ji)(ji)(ji)性(xing)(xing)(xing)判斷(duan)出來(lai)，然后用X10K擋，黑表(biao)筆(bi)(bi)接(jie)二(er)(er)(er)極(ji)(ji)(ji)(ji)管負(fu)極(ji)(ji)(ji)(ji)，紅(hong)表(biao)筆(bi)(bi)接(jie)二(er)(er)(er)極(ji)(ji)(ji)(ji)管正極(ji)(ji)(ji)(ji)，測的(de)阻(zu)值與X1K擋時相比，若(ruo)出現(xian)的(de)反向阻(zu)值很大(da)，為(wei)一(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)管的(de)可能性(xing)(xing)(xing)很大(da)，若(ruo)出現(xian)的(de)反向阻(zu)值變得很小，則(ze)為(wei)穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)管。
2、注意穩(wen)(wen)壓(ya)(ya)二極管(guan)(guan)(guan)(guan)正(zheng)向(xiang)(xiang)使用(yong)(yong)(yong)(yong)與反(fan)向(xiang)(xiang)使用(yong)(yong)(yong)(yong)的(de)區別。穩(wen)(wen)壓(ya)(ya)二極管(guan)(guan)(guan)(guan)正(zheng)向(xiang)(xiang)導(dao)(dao)通使用(yong)(yong)(yong)(yong)時(shi)，與一(yi)(yi)般二極管(guan)(guan)(guan)(guan)正(zheng)向(xiang)(xiang)導(dao)(dao)通使用(yong)(yong)(yong)(yong)時(shi)基(ji)本(ben)相同，正(zheng)向(xiang)(xiang)導(dao)(dao)通后兩(liang)端電(dian)壓(ya)(ya)也(ye)是基(ji)本(ben)不(bu)(bu)變的(de)，都約為0.7V。從(cong)理(li)論上講(jiang)，穩(wen)(wen)壓(ya)(ya)二極管(guan)(guan)(guan)(guan)也(ye)可(ke)正(zheng)向(xiang)(xiang)使用(yong)(yong)(yong)(yong)做穩(wen)(wen)壓(ya)(ya)管(guan)(guan)(guan)(guan)用(yong)(yong)(yong)(yong)，但其穩(wen)(wen)壓(ya)(ya)值將低(di)于1V，且穩(wen)(wen)壓(ya)(ya)性(xing)能也(ye)不(bu)(bu)好，一(yi)(yi)般不(bu)(bu)單獨用(yong)(yong)(yong)(yong)穩(wen)(wen)壓(ya)(ya)管(guan)(guan)(guan)(guan)的(de)正(zheng)向(xiang)(xiang)導(dao)(dao)通特(te)性(xing)來穩(wen)(wen)壓(ya)(ya)，而是用(yong)(yong)(yong)(yong)反(fan)向(xiang)(xiang)擊(ji)穿特(te)性(xing)來穩(wen)(wen)壓(ya)(ya)。反(fan)向(xiang)(xiang)擊(ji)穿電(dian)壓(ya)(ya)值即為穩(wen)(wen)壓(ya)(ya)值。有時(shi)將兩(liang)個(ge)穩(wen)(wen)壓(ya)(ya)管(guan)(guan)(guan)(guan)串聯使用(yong)(yong)(yong)(yong)，一(yi)(yi)個(ge)利(li)用(yong)(yong)(yong)(yong)它的(de)正(zheng)向(xiang)(xiang)特(te)性(xing)，另一(yi)(yi)個(ge)利(li)用(yong)(yong)(yong)(yong)它的(de)反(fan)向(xiang)(xiang)特(te)性(xing)，則既能穩(wen)(wen)壓(ya)(ya)又(you)可(ke)起(qi)溫度補償作(zuo)用(yong)(yong)(yong)(yong)，以提(ti)高(gao)穩(wen)(wen)壓(ya)(ya)效果。
3、要注意限流(liu)電(dian)(dian)阻的作用及阻值(zhi)大(da)小的影響(xiang)。在(zai)(zai)穩壓二極(ji)管(guan)(guan)穩壓電(dian)(dian)路中，一般都要串接一個(ge)電(dian)(dian)阻R，如(ru)圖(tu)1或2示。該(gai)電(dian)(dian)阻在(zai)(zai)電(dian)(dian)路中起限流(liu)和(he)提高穩壓效果(guo)的作用。若不加(jia)該(gai)電(dian)(dian)阻即當R=0時，容(rong)易燒壞穩壓管(guan)(guan)，穩壓效果(guo)也會極(ji)差。限流(liu)電(dian)(dian)阻的阻值(zhi)越大(da)，電(dian)(dian)路穩壓性能越好，但輸入與輸出(chu)壓差也會過大(da)，耗(hao)電(dian)(dian)也就越多。
4、要注意(yi)輸(shu)入(ru)與輸(shu)出(chu)的(de)(de)壓(ya)(ya)(ya)差。正常使(shi)用(yong)時，穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)二極(ji)管(guan)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)電(dian)路(lu)的(de)(de)輸(shu)出(chu)電(dian)壓(ya)(ya)(ya)等于(yu)(yu)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管(guan)反向擊穿后兩端(duan)的(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)值(zhi)(zhi)，若輸(shu)入(ru)到穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)電(dian)路(lu)中的(de)(de)電(dian)壓(ya)(ya)(ya)值(zhi)(zhi)小于(yu)(yu)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管(guan)的(de)(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)值(zhi)(zhi)，則電(dian)路(lu)將失去穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)作用(yong)，只有是大于(yu)(yu)關系時，才有穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)作用(yong)，并且壓(ya)(ya)(ya)差越大，限流電(dian)阻(zu)的(de)(de)阻(zu)值(zhi)(zhi)也應越大，否則會損壞穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管(guan)。
5、穩(wen)(wen)壓管可(ke)串(chuan)(chuan)(chuan)聯(lian)使(shi)用(yong)。幾個穩(wen)(wen)壓管串(chuan)(chuan)(chuan)聯(lian)后，可(ke)獲得多個不(bu)(bu)同的(de)穩(wen)(wen)壓值(zhi)，故串(chuan)(chuan)(chuan)聯(lian)使(shi)用(yong)較常見。下面舉例(li)說(shuo)明兩個穩(wen)(wen)壓管串(chuan)(chuan)(chuan)聯(lian)使(shi)用(yong)后，如何(he)求得穩(wen)(wen)壓值(zhi)。若(ruo)一個穩(wen)(wen)壓管的(de)穩(wen)(wen)壓值(zhi)為(wei)5.6V，另一個穩(wen)(wen)壓值(zhi)為(wei)3.6V，設穩(wen)(wen)壓管正向導通(tong)時電壓均為(wei)0.7V，則(ze)串(chuan)(chuan)(chuan)聯(lian)后共有四種不(bu)(bu)同的(de)穩(wen)(wen)壓值(zhi)，如圖1示。
6、穩壓(ya)(ya)(ya)管(guan)(guan)一般不并(bing)聯(lian)使用(yong)。幾個(ge)穩壓(ya)(ya)(ya)管(guan)(guan)并(bing)聯(lian)后(hou)，穩壓(ya)(ya)(ya)值(zhi)將由最低(包括正向導通后(hou)的電壓(ya)(ya)(ya)值(zhi))的一個(ge)來決定。還是以上述兩(liang)個(ge)穩壓(ya)(ya)(ya)管(guan)(guan)為例，來說明穩壓(ya)(ya)(ya)值(zhi)的計算(suan)方法。兩(liang)個(ge)并(bing)聯(lian)后(hou)共有四(si)種情況(kuang)，穩壓(ya)(ya)(ya)值(zhi)只有兩(liang)個(ge)。除(chu)非(fei)特殊情況(kuang)，穩壓(ya)(ya)(ya)二(er)極管(guan)(guan)都不并(bing)聯(lian)使用(yong)。
