穩壓二極管工作(zuo)在反向擊穿(chuan)狀態(tai)時，其兩端的電(dian)壓是(shi)基本不(bu)變(bian)的。利用這(zhe)一性(xing)質，在電(dian)路(lu)里常用于構成(cheng)穩壓電(dian)路(lu)。
穩壓(ya)二極(ji)管構成(cheng)的(de)穩壓(ya)電(dian)路，雖然(ran)穩定度不很高，但卻具有簡(jian)單(dan)、經濟(ji)實(shi)用的(de)優點，因(yin)而應用非常廣泛。
在實際電路中，要使用好穩壓(ya)二極管，應注意如下幾個問題。
1、要(yao)注意一(yi)(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)與(yu)穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)區(qu)(qu)別方(fang)法(fa)。不(bu)(bu)少的(de)(de)(de)(de)一(yi)(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)，特別是玻璃封裝的(de)(de)(de)(de)管(guan)(guan)(guan)，外形(xing)顏色等與(yu)穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)較(jiao)相似(si)，如不(bu)(bu)細心區(qu)(qu)別，就會使用(yong)(yong)錯(cuo)誤。區(qu)(qu)別方(fang)法(fa)是：看(kan)外形(xing)，不(bu)(bu)少穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)為園(yuan)(yuan)柱形(xing)，較(jiao)短粗(cu)，而一(yi)(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)若為園(yuan)(yuan)柱形(xing)的(de)(de)(de)(de)則較(jiao)細長；看(kan)標志，穩(wen)(wen)(wen) 壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)外表(biao)面上(shang)都標有(you)穩(wen)(wen)(wen)壓(ya)值(zhi)，如5V6，表(biao)示穩(wen)(wen)(wen)壓(ya)值(zhi)為5.6V；用(yong)(yong)萬(wan)用(yong)(yong)表(biao)進行測量，根據單向導(dao)電性，用(yong)(yong)X1K擋(dang)(dang)先把(ba)被測二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)正(zheng)負(fu)極(ji)(ji)(ji)(ji)(ji)性判(pan)斷出來，然后用(yong)(yong)X10K擋(dang)(dang)，黑表(biao)筆接(jie)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)負(fu)極(ji)(ji)(ji)(ji)(ji)，紅表(biao)筆接(jie)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)正(zheng)極(ji)(ji)(ji)(ji)(ji)，測的(de)(de)(de)(de)阻(zu)值(zhi)與(yu)X1K擋(dang)(dang)時(shi)相比，若出現的(de)(de)(de)(de)反(fan)向阻(zu)值(zhi)很大，為一(yi)(yi)般(ban)(ban)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)可能性很大，若出現的(de)(de)(de)(de)反(fan)向阻(zu)值(zhi)變得很小，則為穩(wen)(wen)(wen)壓(ya)二(er)(er)(er)極(ji)(ji)(ji)(ji)(ji)管(guan)(guan)(guan)。
2、注意穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)二(er)(er)極(ji)管正向(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)與反向(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)的(de)(de)區(qu)別。穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)二(er)(er)極(ji)管正向(xiang)(xiang)導(dao)通使(shi)(shi)用(yong)(yong)(yong)時(shi)，與一般二(er)(er)極(ji)管正向(xiang)(xiang)導(dao)通使(shi)(shi)用(yong)(yong)(yong)時(shi)基(ji)本(ben)相同，正向(xiang)(xiang)導(dao)通后兩(liang)(liang)端電壓(ya)(ya)(ya)也(ye)是基(ji)本(ben)不(bu)變的(de)(de)，都約為(wei)0.7V。從理論(lun)上講，穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)二(er)(er)極(ji)管也(ye)可(ke)正向(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)做穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管用(yong)(yong)(yong)，但其穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)值(zhi)將(jiang)低(di)于1V，且穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)性能也(ye)不(bu)好(hao)，一般不(bu)單(dan)獨(du)用(yong)(yong)(yong)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管的(de)(de)正向(xiang)(xiang)導(dao)通特性來穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)，而是用(yong)(yong)(yong)反向(xiang)(xiang)擊穿特性來穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)。反向(xiang)(xiang)擊穿電壓(ya)(ya)(ya)值(zhi)即(ji)為(wei)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)值(zhi)。有時(shi)將(jiang)兩(liang)(liang)個(ge)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)管串聯使(shi)(shi)用(yong)(yong)(yong)，一個(ge)利用(yong)(yong)(yong)它的(de)(de)正向(xiang)(xiang)特性，另一個(ge)利用(yong)(yong)(yong)它的(de)(de)反向(xiang)(xiang)特性，則既能穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)又可(ke)起溫度補(bu)償作(zuo)用(yong)(yong)(yong)，以提高穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)效果。
3、要注意限(xian)流(liu)電阻(zu)的(de)(de)作用及阻(zu)值大(da)小的(de)(de)影響。在穩(wen)壓(ya)(ya)二極管(guan)穩(wen)壓(ya)(ya)電路(lu)中(zhong)，一般都要串接一個(ge)電阻(zu)R，如圖1或2示。該(gai)電阻(zu)在電路(lu)中(zhong)起限(xian)流(liu)和(he)提高穩(wen)壓(ya)(ya)效果的(de)(de)作用。若不加該(gai)電阻(zu)即當(dang)R=0時(shi)，容易燒壞穩(wen)壓(ya)(ya)管(guan)，穩(wen)壓(ya)(ya)效果也(ye)會極差。限(xian)流(liu)電阻(zu)的(de)(de)阻(zu)值越(yue)大(da)，電路(lu)穩(wen)壓(ya)(ya)性能越(yue)好，但輸(shu)入與輸(shu)出(chu)壓(ya)(ya)差也(ye)會過大(da)，耗電也(ye)就越(yue)多。
4、要注(zhu)意輸(shu)入與(yu)輸(shu)出的(de)壓(ya)(ya)(ya)差(cha)(cha)。正常(chang)使用時，穩(wen)(wen)壓(ya)(ya)(ya)二極管穩(wen)(wen)壓(ya)(ya)(ya)電路(lu)(lu)的(de)輸(shu)出電壓(ya)(ya)(ya)等于穩(wen)(wen)壓(ya)(ya)(ya)管反向擊穿(chuan)后兩端的(de)穩(wen)(wen)壓(ya)(ya)(ya)值(zhi)(zhi)，若輸(shu)入到穩(wen)(wen)壓(ya)(ya)(ya)電路(lu)(lu)中的(de)電壓(ya)(ya)(ya)值(zhi)(zhi)小于穩(wen)(wen)壓(ya)(ya)(ya)管的(de)穩(wen)(wen)壓(ya)(ya)(ya)值(zhi)(zhi)，則電路(lu)(lu)將(jiang)失去穩(wen)(wen)壓(ya)(ya)(ya)作(zuo)用，只有是大(da)(da)于關系時，才有穩(wen)(wen)壓(ya)(ya)(ya)作(zuo)用，并且壓(ya)(ya)(ya)差(cha)(cha)越大(da)(da)，限流電阻的(de)阻值(zhi)(zhi)也應(ying)越大(da)(da)，否(fou)則會損(sun)壞穩(wen)(wen)壓(ya)(ya)(ya)管。
5、穩(wen)壓(ya)(ya)管可(ke)串(chuan)聯(lian)使(shi)用(yong)。幾個(ge)穩(wen)壓(ya)(ya)管串(chuan)聯(lian)后，可(ke)獲得多個(ge)不同(tong)的穩(wen)壓(ya)(ya)值，故(gu)串(chuan)聯(lian)使(shi)用(yong)較常見。下面舉(ju)例說明兩個(ge)穩(wen)壓(ya)(ya)管串(chuan)聯(lian)使(shi)用(yong)后，如何求(qiu)得穩(wen)壓(ya)(ya)值。若一(yi)個(ge)穩(wen)壓(ya)(ya)管的穩(wen)壓(ya)(ya)值為5.6V，另(ling)一(yi)個(ge)穩(wen)壓(ya)(ya)值為3.6V，設穩(wen)壓(ya)(ya)管正向導通時(shi)電(dian)壓(ya)(ya)均為0.7V，則串(chuan)聯(lian)后共(gong)有四(si)種不同(tong)的穩(wen)壓(ya)(ya)值，如圖1示。
6、穩(wen)(wen)壓(ya)(ya)管一般不并聯(lian)使用。幾個(ge)(ge)穩(wen)(wen)壓(ya)(ya)管并聯(lian)后(hou)，穩(wen)(wen)壓(ya)(ya)值(zhi)將由(you)最低(包括正向導通后(hou)的電壓(ya)(ya)值(zhi))的一個(ge)(ge)來決定。還(huan)是以上述(shu)兩個(ge)(ge)穩(wen)(wen)壓(ya)(ya)管為例，來說明穩(wen)(wen)壓(ya)(ya)值(zhi)的計(ji)算方法。兩個(ge)(ge)并聯(lian)后(hou)共有(you)四種情況(kuang)，穩(wen)(wen)壓(ya)(ya)值(zhi)只有(you)兩個(ge)(ge)。除非特殊情況(kuang)，穩(wen)(wen)壓(ya)(ya)二極管都不并聯(lian)使用。
