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三端稳压管,直流稳压电源

三(san)端稳压管就是提供稳定的(de)电压给后级电路，比如(ru)给单片机(ji)提供稳定的(de)3V或者5V电源，这样(yang)单片机(ji)才可以(yi)稳定的(de)运行。

三(san)端(duan)稳压管顾名(ming)思义，就(jiu)是有三(san)个(ge)端(duan)口的(de)稳压器，一般是输入电(dian)压，输出电(dian)压，地三(san)个(ge)端(duan)口，只(zhi)需(xu)要外围(wei)简单几(ji)个(ge)电(dian)容即(ji)可，使用简单方便。

三端稳压管实现直流稳压电源的设计

从左往右开始数第一(yi)个(ge)为(wei)(wei)带(dai)金属(shu)外壳的(de)稳压器，由于集电极(ji)的(de)面积较大，因此能够大功(gong)(gong)率的(de)工(gong)作，第二个(ge)图(tu)片(pian)(pian)是(shi)我(wo)们(men)常见到(dao)的(de)三端稳压管的(de)形(xing)(xing)状，下(xia)面有三个(ge)输出引脚，在图(tu)中我(wo)们(men)也(ye)能够很清(qing)晰地看到(dao)各(ge)个(ge)引脚的(de)功(gong)(gong)能，第三张图(tu)片(pian)(pian)就是(shi)我(wo)们(men)在电路中见到(dao)的(de)形(xing)(xing)式(shi)，总(zong)之这三张图(tu)片(pian)(pian)就是(shi)为(wei)(wei)了(le)描述三端稳压管三个(ge)引脚的(de)功(gong)(gong)能。

三端稳(wen)(wen)压(ya)(ya)(ya)(ya)管(guan)(guan)大(da)体上可以分(fen)为两大(da)种分(fen)别为78xx系列(lie)还(hai)有79xx系列(lie)，其中前(qian)者使输(shu)出(chu)稳(wen)(wen)定(ding)正电(dian)(dian)压(ya)(ya)(ya)(ya)xx表示的(de)(de)(de)稳(wen)(wen)定(ding)电(dian)(dian)压(ya)(ya)(ya)(ya)数(shu)值，例如(ru)7805那就是(shi)(shi)5v的(de)(de)(de)稳(wen)(wen)压(ya)(ya)(ya)(ya)管(guan)(guan)，7812就是(shi)(shi)12v的(de)(de)(de)稳(wen)(wen)压(ya)(ya)(ya)(ya)管(guan)(guan)，79系列(lie)的(de)(de)(de)也是(shi)(shi)如(ru)此但是(shi)(shi)稳(wen)(wen)定(ding)电(dian)(dian)压(ya)(ya)(ya)(ya)的(de)(de)(de)是(shi)(shi)负值，例如(ru)7905这里的(de)(de)(de)输(shu)出(chu)稳(wen)(wen)定(ding)电(dian)(dian)压(ya)(ya)(ya)(ya)值就是(shi)(shi)负5v，7912这里的(de)(de)(de)输(shu)出(chu)稳(wen)(wen)定(ding)电(dian)(dian)压(ya)(ya)(ya)(ya)值就是(shi)(shi)负12v。

三端稳压(ya)管的(de)(de)种类还(hai)是(shi)比较多的(de)(de)，一般在(zai)5-24v之间，像(xiang)5V、6V、7V、8V、9V、10V、12V、15V、18V和24V都是(shi)我们在(zai)电(dian)路设计中经常会用(yong)到的(de)(de)，负电(dian)压(ya)也是(shi)如此，可以认为这两个管子是(shi)互(hu)补对称的(de)(de)。

那么(me)三端稳压管的通(tong)用电路是什么(me)样的呢？来看下常用原理图

电路图还是(shi)(shi)比较简单的(de)，我们(men)可以(yi)很(hen)直观的(de)看到有电容C1、C0、还有三(san)端(duan)稳压管(guan)，这里的(de)三(san)端(duan)稳压管(guan)选(xuan)(xuan)用(yong)几(ji)(ji)伏(fu)的(de)，那么输出(chu)电压就(jiu)对应几(ji)(ji)伏(fu)的(de)，此外我们(men)在选(xuan)(xuan)用(yong)的(de)时候，电容C1和(he)C0都不(bu)宜(yi)过大，一般C1取(qu)0.33uf，C0取(qu)0.1uf，如果在设计的(de)过程(cheng)中(zhong)材料(liao)急缺，没有电容，不(bu)加也(ye)是(shi)(shi)可以(yi)的(de)，但是(shi)(shi)输出(chu)端(duan)的(de)电压波形不(bu)是(shi)(shi)很(hen)好(hao)，也(ye)是(shi)(shi)能够实现(xian)稳压只是(shi)(shi)效果不(bu)好(hao)。

此外(wai)还要注意一下(xia)，由于三端稳压(ya)(ya)管只能实现降压(ya)(ya)稳压(ya)(ya)，所以(yi)(yi)输(shu)入电压(ya)(ya)一定要大于输(shu)出电压(ya)(ya)，一般要高于输(shu)出电压(ya)(ya)2v左右(you)，在2v-5v之间(jian)都是效果较好的，大家可以(yi)(yi)根(gen)据实际情况进(jin)行选择。

其实三端(duan)稳(wen)压管不(bu)单单能够实现稳(wen)压，也是(shi)(shi)可(ke)以实现输(shu)出电压可(ke)调的，但是(shi)(shi)最(zui)好还是(shi)(shi)不(bu)要这(zhei)样，如(ru)果(guo)实现没有办法，可(ke)以选择这(zhei)种(zhong)方(fang)法，我也把原理图分享给(ji)大家，大家可(ke)以参考(kao)一下。

输出电压公式(shi)为

U0'就是(shi)三端稳压(ya)管的稳定(ding)电(dian)压(ya)。

三端稳压管接线说明

输出电流小于或等(deng)于1A.

三端稳压管是一种直到临界反向击(ji)(ji)穿(chuan)电(dian)(dian)压前都(dou)具有很高(gao)电(dian)(dian)阻的半导体(ti)器件。稳压管在(zai)反向击(ji)(ji)穿(chuan)时，在(zai)一定的电(dian)(dian)流范围内（或者(zhe)说(shuo)在(zai)一定功率损耗范围内），端电(dian)(dian)压几乎不(bu)变，表(biao)现出稳压特性(xing)，因而广泛应(ying)用于稳压电(dian)(dian)源与限幅电(dian)(dian)路之中。

因为固定三端稳(wen)压(ya)器属(shu)于串联(lian)型(xing)稳(wen)压(ya)电路，因此它的原理等同(tong)于串联(lian)型(xing)稳(wen)压(ya)电路。

其(qi)(qi)中R1、Rp、R2组(zu)(zu)成的(de)(de)分压(ya)(ya)器是取样电(dian)(dian)(dian)(dian)(dian)(dian)路，从输出(chu)端(duan)取出(chu)部分电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)UB2作(zuo)为(wei)取样电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)加至三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)T2的(de)(de)基极(ji)(ji)(ji)(ji)。稳(wen)(wen)(wen)压(ya)(ya)管(guan)(guan)Dz以其(qi)(qi)稳(wen)(wen)(wen)定(ding)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)Uz作(zuo)为(wei)基准(zhun)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)，加在(zai)T2的(de)(de)发(fa)射极(ji)(ji)(ji)(ji)上。R3是稳(wen)(wen)(wen)压(ya)(ya)管(guan)(guan)的(de)(de)限(xian)流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)阻。三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)T2组(zu)(zu)成比较(jiao)放(fang)大电(dian)(dian)(dian)(dian)(dian)(dian)路，它将取样电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)UB2与(yu)基准(zhun)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)Uz加以比较(jiao)和放(fang)大，再去(qu)控制三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)T1的(de)(de)基极(ji)(ji)(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)位。输入(ru)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)Ui加在(zai)三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)T1与(yu)负(fu)载(zai)RL相串(chuan)联(lian)的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)路上，因(yin)此，改(gai)变T1集电(dian)(dian)(dian)(dian)(dian)(dian)极(ji)(ji)(ji)(ji)间的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)降UCE1便可调(diao)节(jie)RL两端(duan)的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)Uo。也就是说(shuo)，稳(wen)(wen)(wen)压(ya)(ya)电(dian)(dian)(dian)(dian)(dian)(dian)路的(de)(de)输出(chu)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)Uo可以通过三(san)极(ji)(ji)(ji)(ji)管(guan)(guan)T1加以调(diao)节(jie)，所以T1称为(wei)调(diao)整管(guan)(guan)。由(you)于调(diao)整元件是晶(jing)体管(guan)(guan)管(guan)(guan)，而(er)且在(zai)电(dian)(dian)(dian)(dian)(dian)(dian)路中与(yu)负(fu)载(zai)相串(chuan)联(lian)，故称为(wei)晶(jing)体管(guan)(guan)串(chuan)联(lian)型稳(wen)(wen)(wen)压(ya)(ya)电(dian)(dian)(dian)(dian)(dian)(dian)路。电(dian)(dian)(dian)(dian)(dian)(dian)阻R4和T1的(de)(de)基极(ji)(ji)(ji)(ji)偏置电(dian)(dian)(dian)(dian)(dian)(dian)阻，也是T2的(de)(de)集电(dian)(dian)(dian)(dian)(dian)(dian)极(ji)(ji)(ji)(ji)负(fu)载(zai)电(dian)(dian)(dian)(dian)(dian)(dian)阻。

当电(dian)(dian)网电(dian)(dian)压降(jiang)低或负(fu)载电(dian)(dian)阻(zu)减(jian)小而(er)使输出端(duan)电(dian)(dian)压有所下(xia)降(jiang)时(shi)，其(qi)取样电(dian)(dian)压UB2相应减(jian)小，T2基极(ji)电(dian)(dian)位下(xia)降(jiang)。但因T2发(fa)射极(ji)电(dian)(dian)位既稳压管的稳定Uz保持不(bu)变(bian)，所以(yi)发(fa)射极(ji)电(dian)(dian)压UBE2减(jian)小，导(dao)致(zhi)(zhi)T2集(ji)(ji)电(dian)(dian)极(ji)电(dian)(dian)流减(jian)小而(er)集(ji)(ji)电(dian)(dian)极(ji)电(dian)(dian)位Uc2升(sheng)(sheng)高。由(you)于放大管T2的集(ji)(ji)电(dian)(dian)极(ji)与调整管T1的基极(ji)接在一起，故T1基极(ji)电(dian)(dian)位升(sheng)(sheng)高，导(dao)致(zhi)(zhi)集(ji)(ji)电(dian)(dian)极(ji)电(dian)(dian)流增大而(er)管压降(jiang)UCE1减(jian)小。因为T1与RL串联，所以(yi)，输出电(dian)(dian)压Uo基本(ben)不(bu)变(bian)。

同理，当(dang)电网(wang)电压或负载(zai)发生(sheng)变化引起输(shu)出电压Uo增(zeng)大(da)(da)时(shi)，通过(guo)取样、比较(jiao)放大(da)(da)、调整(zheng)等过(guo)程(cheng)，将使调整(zheng)调整(zheng)管(guan)的(de)管(guan)压降UCE1增(zeng)加，结果(guo)抑制了输(shu)出端电压的(de)增(zeng)大(da)(da)，输(shu)出电压仍基本(ben)保持不变。

调(diao)节(jie)电(dian)(dian)位器(qi)Rp，可对输出电(dian)(dian)压进行微(wei)调(diao)。调(diao)整管T1与(yu)负载电(dian)(dian)阻RL组成(cheng)的是射极输出电(dian)(dian)路(lu)，所以具(ju)有稳定输出电(dian)(dian)压的特点。

在(zai)串联型稳压电(dian)(dian)源(yuan)电(dian)(dian)路(lu)的工作(zuo)过程中，要求调(diao)整(zheng)管(guan)(guan)始终处(chu)在(zai)放大(da)状态。通过调(diao)整(zheng)管(guan)(guan)的电(dian)(dian)流等(deng)于负载电(dian)(dian)流，因此必须(xu)选用适当的大(da)功率(lv)管(guan)(guan)作(zuo)调(diao)整(zheng)管(guan)(guan)，并按(an)规定安(an)装散热装置。为了防止(zhi)短路(lu)或(huo)长期过载烧(shao)坏(huai)调(diao)整(zheng)管(guan)(guan)，在(zai)直流稳压器(qi)中一般还设有短路(lu)保护和过载保护等(deng)电(dian)(dian)路(lu)。

7809三端稳压器接线说明

通(tong)常(chang)以标识(shi)面为准左进右出(chu)(chu)中间接地。7809三端(duan)稳压(ya)器有以下几部分组成：1、调(diao)整电(dian)(dian)(dian)(dian)(dian)路;2、取(qu)(qu)样电(dian)(dian)(dian)(dian)(dian)路;3、取(qu)(qu)样放大(da);;稳压(ya)过程：设(she)输(shu)(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)(dian)(dian)压(ya)已(yi)达(da)到预(yu)设(she)电(dian)(dian)(dian)(dian)(dian)压(ya)。当输(shu)(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)(dian)(dian)压(ya)变化(hua)时，取(qu)(qu)样电(dian)(dian)(dian)(dian)(dian)路取(qu)(qu)得样本经取(qu)(qu)样放大(da)与基准电(dian)(dian)(dian)(dian)(dian)路比较判(pan)断输(shu)(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)(dian)(dian)压(ya)是向高了变化(hua)还是向低(di)了变化(hua)，由此控制(zhi)调(diao)整电(dian)(dian)(dian)(dian)(dian)路工作，促(cu)使调(diao)整电(dian)(dian)(dian)(dian)(dian)路调(diao)整输(shu)(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)(dian)(dian)压(ya)向低(di)或高变化(hua)，直(zhi)到输(shu)(shu)(shu)出(chu)(chu)达(da)到预(yu)设(she)电(dian)(dian)(dian)(dian)(dian)压(ya)。

1、7812三(san)端(duan)稳压器接线：

左(zuo)边输(shu)入、中(zhong)间地线、右边输(shu)出

2、1912三端稳压器(qi)接线

左边(bian)地线(xian)、中间(jian)输(shu)入、右边(bian)输(shu)出

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