穩壓二極管工作在反向(xiang)擊(ji)穿狀態時，其(qi)兩端的(de)(de)電(dian)(dian)壓是基本(ben)不變的(de)(de)。利用這一性質，在電(dian)(dian)路里常(chang)用于(yu)構成穩壓電(dian)(dian)路。
穩壓(ya)二極管構成(cheng)的(de)穩壓(ya)電路，雖然穩定度不很高，但(dan)卻具有簡單(dan)、經(jing)濟實(shi)用的(de)優點(dian)，因而應用非常廣(guang)泛。
在實(shi)際電路中，要使用(yong)好(hao)穩壓二(er)極管，應注意如下(xia)幾(ji)個問題。
1、要注意一般二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)與(yu)穩(wen)(wen)壓(ya)(ya)(ya)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)的(de)區(qu)別方法。不(bu)少(shao)的(de)一般二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)，特(te)別是(shi)玻璃(li)封裝的(de)管(guan)(guan)(guan)，外(wai)形(xing)顏色等與(yu)穩(wen)(wen)壓(ya)(ya)(ya)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)較相似，如不(bu)細心區(qu)別，就會使用(yong)錯誤。區(qu)別方法是(shi)：看(kan)外(wai)形(xing)，不(bu)少(shao)穩(wen)(wen)壓(ya)(ya)(ya)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)為園柱形(xing)，較短粗，而一般二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)若為園柱形(xing)的(de)則較細長；看(kan)標(biao)志，穩(wen)(wen) 壓(ya)(ya)(ya)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)的(de)外(wai)表(biao)(biao)面(mian)上都(dou)標(biao)有穩(wen)(wen)壓(ya)(ya)(ya)值(zhi)，如5V6，表(biao)(biao)示穩(wen)(wen)壓(ya)(ya)(ya)值(zhi)為5.6V；用(yong)萬用(yong)表(biao)(biao)進行測(ce)量，根據(ju)單向(xiang)導(dao)電性，用(yong)X1K擋先把被測(ce)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)的(de)正負極(ji)(ji)性判斷出來(lai)，然后用(yong)X10K擋，黑表(biao)(biao)筆接二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)負極(ji)(ji)，紅表(biao)(biao)筆接二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)正極(ji)(ji)，測(ce)的(de)阻值(zhi)與(yu)X1K擋時相比(bi)，若出現的(de)反(fan)向(xiang)阻值(zhi)很(hen)(hen)大，為一般二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)的(de)可能性很(hen)(hen)大，若出現的(de)反(fan)向(xiang)阻值(zhi)變(bian)得很(hen)(hen)小，則為穩(wen)(wen)壓(ya)(ya)(ya)二(er)(er)(er)(er)極(ji)(ji)管(guan)(guan)(guan)。
2、注意穩(wen)(wen)(wen)(wen)壓(ya)(ya)二(er)極管正(zheng)(zheng)(zheng)向(xiang)(xiang)使(shi)用(yong)(yong)(yong)(yong)(yong)與(yu)反(fan)向(xiang)(xiang)使(shi)用(yong)(yong)(yong)(yong)(yong)的(de)區(qu)別(bie)。穩(wen)(wen)(wen)(wen)壓(ya)(ya)二(er)極管正(zheng)(zheng)(zheng)向(xiang)(xiang)導(dao)(dao)通(tong)使(shi)用(yong)(yong)(yong)(yong)(yong)時(shi)(shi)，與(yu)一(yi)般二(er)極管正(zheng)(zheng)(zheng)向(xiang)(xiang)導(dao)(dao)通(tong)使(shi)用(yong)(yong)(yong)(yong)(yong)時(shi)(shi)基(ji)本(ben)相同，正(zheng)(zheng)(zheng)向(xiang)(xiang)導(dao)(dao)通(tong)后(hou)兩端電壓(ya)(ya)也(ye)是基(ji)本(ben)不變(bian)的(de)，都約(yue)為0.7V。從(cong)理(li)論上(shang)講，穩(wen)(wen)(wen)(wen)壓(ya)(ya)二(er)極管也(ye)可(ke)正(zheng)(zheng)(zheng)向(xiang)(xiang)使(shi)用(yong)(yong)(yong)(yong)(yong)做穩(wen)(wen)(wen)(wen)壓(ya)(ya)管用(yong)(yong)(yong)(yong)(yong)，但其(qi)穩(wen)(wen)(wen)(wen)壓(ya)(ya)值將低于1V，且穩(wen)(wen)(wen)(wen)壓(ya)(ya)性(xing)(xing)能也(ye)不好，一(yi)般不單獨用(yong)(yong)(yong)(yong)(yong)穩(wen)(wen)(wen)(wen)壓(ya)(ya)管的(de)正(zheng)(zheng)(zheng)向(xiang)(xiang)導(dao)(dao)通(tong)特(te)性(xing)(xing)來穩(wen)(wen)(wen)(wen)壓(ya)(ya)，而是用(yong)(yong)(yong)(yong)(yong)反(fan)向(xiang)(xiang)擊(ji)穿特(te)性(xing)(xing)來穩(wen)(wen)(wen)(wen)壓(ya)(ya)。反(fan)向(xiang)(xiang)擊(ji)穿電壓(ya)(ya)值即為穩(wen)(wen)(wen)(wen)壓(ya)(ya)值。有(you)時(shi)(shi)將兩個穩(wen)(wen)(wen)(wen)壓(ya)(ya)管串聯使(shi)用(yong)(yong)(yong)(yong)(yong)，一(yi)個利(li)(li)用(yong)(yong)(yong)(yong)(yong)它的(de)正(zheng)(zheng)(zheng)向(xiang)(xiang)特(te)性(xing)(xing)，另一(yi)個利(li)(li)用(yong)(yong)(yong)(yong)(yong)它的(de)反(fan)向(xiang)(xiang)特(te)性(xing)(xing)，則(ze)既能穩(wen)(wen)(wen)(wen)壓(ya)(ya)又可(ke)起溫度補償(chang)作用(yong)(yong)(yong)(yong)(yong)，以(yi)提高穩(wen)(wen)(wen)(wen)壓(ya)(ya)效果。
3、要(yao)注意(yi)限(xian)流(liu)電(dian)(dian)阻的(de)(de)作用(yong)及阻值大小的(de)(de)影(ying)響。在穩壓(ya)二極管(guan)穩壓(ya)電(dian)(dian)路中(zhong)，一(yi)般都(dou)要(yao)串接一(yi)個電(dian)(dian)阻R，如圖(tu)1或2示。該電(dian)(dian)阻在電(dian)(dian)路中(zhong)起限(xian)流(liu)和提高穩壓(ya)效果的(de)(de)作用(yong)。若(ruo)不加(jia)該電(dian)(dian)阻即當(dang)R=0時，容(rong)易燒(shao)壞穩壓(ya)管(guan)，穩壓(ya)效果也會(hui)極差。限(xian)流(liu)電(dian)(dian)阻的(de)(de)阻值越大，電(dian)(dian)路穩壓(ya)性(xing)能越好(hao)，但輸入與輸出壓(ya)差也會(hui)過大，耗電(dian)(dian)也就越多。
4、要注意輸(shu)(shu)入與輸(shu)(shu)出的(de)壓(ya)(ya)(ya)(ya)(ya)差。正常使用時(shi)，穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)二(er)極管穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)路(lu)的(de)輸(shu)(shu)出電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)等(deng)于穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)管反向(xiang)擊穿后兩端的(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)值(zhi)，若輸(shu)(shu)入到穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)路(lu)中的(de)電(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)值(zhi)小于穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)管的(de)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)值(zhi)，則(ze)(ze)電(dian)(dian)路(lu)將(jiang)失去穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)作用，只有(you)是大于關系時(shi)，才(cai)有(you)穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)作用，并且壓(ya)(ya)(ya)(ya)(ya)差越大，限(xian)流電(dian)(dian)阻的(de)阻值(zhi)也應越大，否則(ze)(ze)會損壞穩(wen)(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)(ya)管。
5、穩(wen)(wen)(wen)壓(ya)管可(ke)串(chuan)(chuan)聯使(shi)用。幾(ji)個穩(wen)(wen)(wen)壓(ya)管串(chuan)(chuan)聯后(hou)，可(ke)獲(huo)得(de)多個不同的(de)穩(wen)(wen)(wen)壓(ya)值，故串(chuan)(chuan)聯使(shi)用較常見(jian)。下面舉例說明(ming)兩個穩(wen)(wen)(wen)壓(ya)管串(chuan)(chuan)聯使(shi)用后(hou)，如何求得(de)穩(wen)(wen)(wen)壓(ya)值。若(ruo)一個穩(wen)(wen)(wen)壓(ya)管的(de)穩(wen)(wen)(wen)壓(ya)值為5.6V，另一個穩(wen)(wen)(wen)壓(ya)值為3.6V，設穩(wen)(wen)(wen)壓(ya)管正向導通時(shi)電壓(ya)均(jun)為0.7V，則串(chuan)(chuan)聯后(hou)共有四種(zhong)不同的(de)穩(wen)(wen)(wen)壓(ya)值，如圖1示。
6、穩(wen)(wen)(wen)壓(ya)管(guan)一(yi)般(ban)不(bu)(bu)并(bing)(bing)聯使用。幾個(ge)穩(wen)(wen)(wen)壓(ya)管(guan)并(bing)(bing)聯后，穩(wen)(wen)(wen)壓(ya)值(zhi)(zhi)將(jiang)由最(zui)低(包括正向導通(tong)后的電壓(ya)值(zhi)(zhi))的一(yi)個(ge)來(lai)(lai)決定。還(huan)是以上述兩個(ge)穩(wen)(wen)(wen)壓(ya)管(guan)為例，來(lai)(lai)說(shuo)明穩(wen)(wen)(wen)壓(ya)值(zhi)(zhi)的計算(suan)方(fang)法。兩個(ge)并(bing)(bing)聯后共有(you)四種情況，穩(wen)(wen)(wen)壓(ya)值(zhi)(zhi)只有(you)兩個(ge)。除(chu)非特殊情況，穩(wen)(wen)(wen)壓(ya)二極(ji)管(guan)都不(bu)(bu)并(bing)(bing)聯使用。
