穩(wen)壓二極管工作(zuo)在反向擊穿狀態時，其兩端的電(dian)壓是基本不變的。利用這一性質，在電(dian)路里常用于構成(cheng)穩(wen)壓電(dian)路。
穩壓二極管構成的穩壓電路，雖(sui)然穩定度不很高(gao)，但卻(que)具有簡單、經濟實(shi)用的優點，因而應用非(fei)常廣泛。
在實(shi)際電路(lu)中，要使用好穩壓二極管(guan)，應(ying)注意(yi)如下幾個問題。
1、要(yao)注(zhu)意一般二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)與穩壓(ya)(ya)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)的(de)(de)(de)區別方法。不少(shao)的(de)(de)(de)一般二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)，特別是玻璃封(feng)裝的(de)(de)(de)管(guan)(guan)(guan)(guan)，外(wai)形(xing)顏色等與穩壓(ya)(ya)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)較(jiao)相似，如不細心區別，就會使用(yong)(yong)錯誤。區別方法是：看(kan)外(wai)形(xing)，不少(shao)穩壓(ya)(ya)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)為園柱形(xing)，較(jiao)短粗，而一般二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)若為園柱形(xing)的(de)(de)(de)則較(jiao)細長(chang)；看(kan)標(biao)志，穩 壓(ya)(ya)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)的(de)(de)(de)外(wai)表(biao)(biao)面上都標(biao)有穩壓(ya)(ya)值(zhi)(zhi)，如5V6，表(biao)(biao)示穩壓(ya)(ya)值(zhi)(zhi)為5.6V；用(yong)(yong)萬用(yong)(yong)表(biao)(biao)進行測(ce)量，根據單向(xiang)導電性(xing)，用(yong)(yong)X1K擋(dang)(dang)先把被測(ce)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)的(de)(de)(de)正(zheng)負極(ji)(ji)(ji)性(xing)判(pan)斷出(chu)來，然后用(yong)(yong)X10K擋(dang)(dang)，黑表(biao)(biao)筆接二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)負極(ji)(ji)(ji)，紅表(biao)(biao)筆接二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)正(zheng)極(ji)(ji)(ji)，測(ce)的(de)(de)(de)阻(zu)(zu)值(zhi)(zhi)與X1K擋(dang)(dang)時(shi)相比(bi)，若出(chu)現的(de)(de)(de)反向(xiang)阻(zu)(zu)值(zhi)(zhi)很大(da)，為一般二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)的(de)(de)(de)可能性(xing)很大(da)，若出(chu)現的(de)(de)(de)反向(xiang)阻(zu)(zu)值(zhi)(zhi)變得很小，則為穩壓(ya)(ya)二(er)極(ji)(ji)(ji)管(guan)(guan)(guan)(guan)。
2、注意穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)二(er)極管(guan)(guan)正向(xiang)(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)與反(fan)(fan)向(xiang)(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)的(de)區別。穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)二(er)極管(guan)(guan)正向(xiang)(xiang)(xiang)導(dao)通使(shi)(shi)用(yong)(yong)(yong)時，與一(yi)般二(er)極管(guan)(guan)正向(xiang)(xiang)(xiang)導(dao)通使(shi)(shi)用(yong)(yong)(yong)時基本相同，正向(xiang)(xiang)(xiang)導(dao)通后兩(liang)端電(dian)壓(ya)(ya)(ya)(ya)也是基本不變的(de)，都約為(wei)0.7V。從(cong)理論上講，穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)二(er)極管(guan)(guan)也可正向(xiang)(xiang)(xiang)使(shi)(shi)用(yong)(yong)(yong)做穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)用(yong)(yong)(yong)，但其穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)將低(di)于(yu)1V，且穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)性(xing)(xing)能也不好，一(yi)般不單獨(du)用(yong)(yong)(yong)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)的(de)正向(xiang)(xiang)(xiang)導(dao)通特性(xing)(xing)來(lai)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)，而(er)是用(yong)(yong)(yong)反(fan)(fan)向(xiang)(xiang)(xiang)擊穿特性(xing)(xing)來(lai)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)。反(fan)(fan)向(xiang)(xiang)(xiang)擊穿電(dian)壓(ya)(ya)(ya)(ya)值(zhi)即為(wei)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)值(zhi)。有時將兩(liang)個(ge)(ge)穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)串(chuan)聯使(shi)(shi)用(yong)(yong)(yong)，一(yi)個(ge)(ge)利用(yong)(yong)(yong)它(ta)的(de)正向(xiang)(xiang)(xiang)特性(xing)(xing)，另一(yi)個(ge)(ge)利用(yong)(yong)(yong)它(ta)的(de)反(fan)(fan)向(xiang)(xiang)(xiang)特性(xing)(xing)，則既能穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)又可起溫度補償作(zuo)用(yong)(yong)(yong)，以提高穩(wen)(wen)(wen)壓(ya)(ya)(ya)(ya)效(xiao)果。
3、要(yao)(yao)注意限(xian)流(liu)電阻(zu)的(de)作用(yong)及阻(zu)值(zhi)大小的(de)影響(xiang)。在(zai)(zai)穩(wen)壓二極管(guan)穩(wen)壓電路中，一般都要(yao)(yao)串接一個電阻(zu)R，如圖1或2示。該電阻(zu)在(zai)(zai)電路中起限(xian)流(liu)和提高穩(wen)壓效(xiao)果(guo)的(de)作用(yong)。若不加該電阻(zu)即當R=0時(shi)，容(rong)易燒壞穩(wen)壓管(guan)，穩(wen)壓效(xiao)果(guo)也(ye)會極差。限(xian)流(liu)電阻(zu)的(de)阻(zu)值(zhi)越大，電路穩(wen)壓性(xing)能越好(hao)，但輸(shu)(shu)入與(yu)輸(shu)(shu)出壓差也(ye)會過大，耗電也(ye)就越多(duo)。
4、要注意輸入與輸出(chu)的(de)(de)壓(ya)差。正常使(shi)用(yong)時(shi)(shi)，穩壓(ya)二極管(guan)穩壓(ya)電(dian)路(lu)的(de)(de)輸出(chu)電(dian)壓(ya)等于穩壓(ya)管(guan)反向擊穿后兩端的(de)(de)穩壓(ya)值(zhi)，若輸入到穩壓(ya)電(dian)路(lu)中(zhong)的(de)(de)電(dian)壓(ya)值(zhi)小于穩壓(ya)管(guan)的(de)(de)穩壓(ya)值(zhi)，則電(dian)路(lu)將失去穩壓(ya)作用(yong)，只有是大(da)于關(guan)系(xi)時(shi)(shi)，才有穩壓(ya)作用(yong)，并且(qie)壓(ya)差越大(da)，限流電(dian)阻的(de)(de)阻值(zhi)也應越大(da)，否則會損壞(huai)穩壓(ya)管(guan)。
5、穩壓(ya)(ya)(ya)管(guan)可(ke)串(chuan)(chuan)(chuan)聯(lian)使用(yong)。幾個(ge)(ge)穩壓(ya)(ya)(ya)管(guan)串(chuan)(chuan)(chuan)聯(lian)后，可(ke)獲得多個(ge)(ge)不同的穩壓(ya)(ya)(ya)值(zhi)，故串(chuan)(chuan)(chuan)聯(lian)使用(yong)較常見。下面舉例說明兩個(ge)(ge)穩壓(ya)(ya)(ya)管(guan)串(chuan)(chuan)(chuan)聯(lian)使用(yong)后，如(ru)何(he)求得穩壓(ya)(ya)(ya)值(zhi)。若一個(ge)(ge)穩壓(ya)(ya)(ya)管(guan)的穩壓(ya)(ya)(ya)值(zhi)為(wei)5.6V，另(ling)一個(ge)(ge)穩壓(ya)(ya)(ya)值(zhi)為(wei)3.6V，設穩壓(ya)(ya)(ya)管(guan)正向導通時電(dian)壓(ya)(ya)(ya)均為(wei)0.7V，則串(chuan)(chuan)(chuan)聯(lian)后共有四種(zhong)不同的穩壓(ya)(ya)(ya)值(zhi)，如(ru)圖(tu)1示。
6、穩(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)(guan)一(yi)般不并聯(lian)(lian)使用。幾個(ge)(ge)(ge)穩(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)(guan)并聯(lian)(lian)后，穩(wen)壓(ya)(ya)(ya)(ya)值將由(you)最低(包括正向導通后的電壓(ya)(ya)(ya)(ya)值)的一(yi)個(ge)(ge)(ge)來決定(ding)。還是以上述兩(liang)個(ge)(ge)(ge)穩(wen)壓(ya)(ya)(ya)(ya)管(guan)(guan)(guan)為例，來說明穩(wen)壓(ya)(ya)(ya)(ya)值的計算方(fang)法。兩(liang)個(ge)(ge)(ge)并聯(lian)(lian)后共有四種(zhong)情(qing)況(kuang)，穩(wen)壓(ya)(ya)(ya)(ya)值只有兩(liang)個(ge)(ge)(ge)。除非特殊情(qing)況(kuang)，穩(wen)壓(ya)(ya)(ya)(ya)二極管(guan)(guan)(guan)都不并聯(lian)(lian)使用。
