利盈娱乐(中国)创新平台有限公司

三(san)端稳(wen)压管(guan)是一种(zhong)直(zhi)到临界反(fan)向击(ji)(ji)穿电(dian)(dian)压前都具有很(hen)高电(dian)(dian)阻(zu)的(de)半导体(ti)器件。稳(wen)压管(guan)在(zai)反(fan)向击(ji)(ji)穿时，在(zai)一定的(de)电(dian)(dian)流范围(wei)内(nei)（或者说在(zai)一定功率损(sun)耗范围(wei)内(nei)），端电(dian)(dian)压几(ji)乎(hu)不变(bian)，表(biao)现(xian)出稳(wen)压特(te)性，因而(er)广(guang)泛(fan)应(ying)用于稳(wen)压电(dian)(dian)源与限幅(fu)电(dian)(dian)路之(zhi)中。

主要有两种，一种输出电压是固定的，另一种输出电压是可调的，称为可调输出三端稳压管产品，其基本原理相同，均采用串联型稳压电路。因为固定它属于串联型稳压电路，因此它的原理等同于串联型稳压电路。
其中R1、Rp、R2组成的分压器是取样电路，从输出端取出部分电压UB2作为取样电压加至三极管T2的基极。稳压管Dz以其稳定电压Uz作为基准电压，加在T2的发射极上。R3是稳压管的限流电阻。三极管T2组成比较放大电路，它将取样电压UB2与基准电压Uz加以比较和放大，再去控制三极管T1的基极电位。输入电压Ui加在三极管T1与负载RL相串联的电路上，因此，改变T1集电极间的电压降UCE1便可调节RL两端的电压Uo。也就是说，稳压电路的输出电压Uo可以通过三极管T1加以调节，所以T1称为调整管。由于调整元件是晶体管管，而且在电路中与负载相串联，故称为晶体管串联型稳压电路。电阻R4和T1的基极偏置电阻，也是T2的集电极负载电阻。

当电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)降(jiang)低或负(fu)载(zai)电(dian)(dian)(dian)(dian)阻(zu)减(jian)小(xiao)(xiao)而(er)使输(shu)(shu)出(chu)(chu)(chu)端电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)有所(suo)下降(jiang)时(shi)，其取(qu)样(yang)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)UB2相应减(jian)小(xiao)(xiao)，T2基(ji)(ji)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)位(wei)(wei)下降(jiang)。但因(yin)T2发(fa)射(she)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)位(wei)(wei)既(ji)稳压(ya)(ya)(ya)管的(de)(de)(de)稳定Uz保持不(bu)(bu)变(bian)，所(suo)以(yi)(yi)(yi)发(fa)射(she)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)UBE2减(jian)小(xiao)(xiao)，导致T2集(ji)电(dian)(dian)(dian)(dian)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)流减(jian)小(xiao)(xiao)而(er)集(ji)电(dian)(dian)(dian)(dian)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)位(wei)(wei)Uc2升(sheng)高(gao)。由于放(fang)大(da)管T2的(de)(de)(de)集(ji)电(dian)(dian)(dian)(dian)极(ji)(ji)(ji)与(yu)调(diao)(diao)(diao)整(zheng)(zheng)(zheng)管T1的(de)(de)(de)基(ji)(ji)极(ji)(ji)(ji)接在一起，故T1基(ji)(ji)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)位(wei)(wei)升(sheng)高(gao)，导致集(ji)电(dian)(dian)(dian)(dian)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)流增(zeng)大(da)而(er)管压(ya)(ya)(ya)降(jiang)UCE1减(jian)小(xiao)(xiao)。因(yin)为T1与(yu)RL串联，所(suo)以(yi)(yi)(yi)，输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)Uo基(ji)(ji)本不(bu)(bu)变(bian)。同(tong)理,当电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)或负(fu)载(zai)发(fa)生(sheng)变(bian)化(hua)引起输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)Uo增(zeng)大(da)时(shi)，通过取(qu)样(yang)、比(bi)较放(fang)大(da)、调(diao)(diao)(diao)整(zheng)(zheng)(zheng)等过程，将使调(diao)(diao)(diao)整(zheng)(zheng)(zheng)调(diao)(diao)(diao)整(zheng)(zheng)(zheng)管的(de)(de)(de)管压(ya)(ya)(ya)降(jiang)UCE1增(zeng)加，结果抑制(zhi)了输(shu)(shu)出(chu)(chu)(chu)端电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)的(de)(de)(de)增(zeng)大(da)，输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)仍基(ji)(ji)本保持不(bu)(bu)变(bian)。调(diao)(diao)(diao)节电(dian)(dian)(dian)(dian)位(wei)(wei)器(qi)Rp，可对输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)进行微(wei)调(diao)(diao)(diao)。调(diao)(diao)(diao)整(zheng)(zheng)(zheng)管T1与(yu)负(fu)载(zai)电(dian)(dian)(dian)(dian)阻(zu)RL组成的(de)(de)(de)是(shi)射(she)极(ji)(ji)(ji)输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)路，所(suo)以(yi)(yi)(yi)具(ju)有稳定输(shu)(shu)出(chu)(chu)(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)的(de)(de)(de)特点。

在串联型稳压电源电路的工作过程中，要求调整管始终处在放大状态。通过调整管的电流等于负载电流，因此必须选用适当的大功率管作调整管，并按规定安装散热装置。为了防止短路或长期过载烧坏调整管，在直流稳压器中一般还设有短路保护和过载保护等电路。
在使用(yong)时必须注意：(VI)和(Vo)之间(jian)的关系，以(yi)7805为例，该固定输(shu)(shu)出(chu)电(dian)压(ya)是5V，而输(shu)(shu)入电(dian)压(ya)至少(shao)大(da)(da)(da)于7V，这样输(shu)(shu)入/输(shu)(shu)出(chu)之间(jian)有2－3V及(ji)以(yi)上的压(ya)差。使调(diao)整(zheng)管保(bao)证工作在放大(da)(da)(da)区。但压(ya)差取(qu)得大(da)(da)(da)时，又(you)(you)会增加(jia)集成块(kuai)的功(gong)耗(hao)，所以(yi)，两者应兼顾，即既保(bao)证在最大(da)(da)(da)负载电(dian)流时调(diao)整(zheng)管不(bu)进入饱和，又(you)(you)不(bu)致(zhi)于功(gong)耗(hao)偏大(da)(da)(da)。另外一般在三端(duan)稳压(ya)管的输(shu)(shu)入输(shu)(shu)出(chu)端(duan)接一个二极管，用(yong)来防(fang)止输(shu)(shu)入端(duan)短路时,输(shu)(shu)出(chu)端(duan)存储(chu)的电(dian)荷(he)通过稳压(ya)器,而损坏器件。

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