7812中文资料

三(san)端(duan)(duan)稳(wen)压(ya)集成电(dian)路(lu)(lu)7812。电(dian)子(zi)产(chan)品中，常见(jian)的(de)三(san)端(duan)(duan)稳(wen)压(ya)集成电(dian)路(lu)(lu)有(you)(you)正电(dian)压(ya)输出(chu)(chu)的(de)78××系(xi)列和负电(dian)压(ya)输出(chu)(chu)的(de)79××系(xi)列。顾(gu)名思(si)义，三(san)端(duan)(duan)IC是指这(zhei)种稳(wen)压(ya)用的(de)集成电(dian)路(lu)(lu)，只有(you)(you)三(san)条引脚(jiao)输出(chu)(chu)，分(fen)别是输入(ru)端(duan)(duan)、接地端(duan)(duan)和输出(chu)(chu)端(duan)(duan)。它(ta)的(de)样子(zi)像(xiang)是普(pu)通(tong)的(de)三(san)极管，TO- 220的(de)标准封装，也有(you)(you)9013样子(zi)的(de)T0-92封装。

一、7812简介

用78/79系列三端(duan)稳压IC来(lai)组(zu)成稳压电(dian)源所需的(de)外围元件极少(shao)，电(dian)路内(nei)部还有过(guo)流、过(guo)热(re)及调整管(guan)的(de)保护电(dian)路，使用起来(lai)可靠、方便，而(er)且价格便宜。该(gai)系列集成稳压IC型(xing)号中(zhong)的(de)78或79后面(mian)的(de)数字代表(biao)该(gai)三端(duan)集成稳压电(dian)路的(de)输(shu)出(chu)(chu)电(dian)压，如7806表(biao)示(shi)输(shu)出(chu)(chu)电(dian)压为正6V，7909表(biao)示(shi)输(shu)出(chu)(chu)电(dian)压为角(jiao)9V。

因为(wei)(wei)三端固定集成(cheng)稳(wen)压(ya)电(dian)路的使用(yong)方便(bian)，电(dian)子制作中经常(chang)采用(yong)。最(zui)大输(shu)出(chu)电(dian)滴l. 5A，Ⅻ78Ⅱ系(xi)列(lie)输(shu)出(chu)电(dian)压(ya)分别为(wei)(wei)5V 6V 8V 9V IOV 12V 15V 18V 24V.

二、7812应用范围

在实际应(ying)用(yong)中，应(ying)在三端集成稳压(ya)电(dian)路(lu)上安装足够大的散热器（当然小功(gong)率的条件下不(bu)用(yong)）。当稳压(ya)管(guan)温度过高时，稳压(ya)性(xing)能将变差(cha)，甚至损坏。

当制(zhi)作中需要一(yi)个能输(shu)(shu)出(chu)(chu)1.5A以(yi)上(shang)电(dian)(dian)流的(de)稳(wen)(wen)压电(dian)(dian)源，通常采用几块三端稳(wen)(wen)压电(dian)(dian)路(lu)并联(lian)起来，使其最大输(shu)(shu)出(chu)(chu)电(dian)(dian)演为N个1.5A，但应(ying)用时(shi)需注意：并联(lian)使用的(de)集成稳(wen)(wen)压电(dian)(dian)路(lu)应(ying)采用同一(yi)厂家、同一(yi)批(pi)号的(de)产品(pin)，以(yi)保证参数(shu)的(de)一(yi)致。另外在输(shu)(shu)出(chu)(chu)电(dian)(dian)流上(shang)留有一(yi)定的(de)余量，以(yi)避免个别(bie)集成稳(wen)(wen)压电(dian)(dian)路(lu)失(shi)效时(shi)导致其他电(dian)(dian)路(lu)的(de)连锁(suo)烧毁。

在78/79系列三端稳压(ya)器中最(zui)常应用的是220和(he)T0-202两种封(feng)装(zhuang)这两种封(feng)装(zhuang)的图形(xing)以及引脚序号(hao)、引脚功能如(ru)附图所(suo)示。

图(tu)(tu)中(zhong)(zhong)的引脚(jiao)(jiao)号标注方法是(shi)按照引脚(jiao)(jiao)电(dian)(dian)(dian)位(wei)(wei)从高(gao)到(dao)底(di)的顺(shun)序标注的。这(zhei)样标注便于记忆(yi)。引脚(jiao)(jiao)①为(wei)最(zui)(zui)(zui)高(gao)电(dian)(dian)(dian)位(wei)(wei)，0脚(jiao)(jiao)为(wei)最(zui)(zui)(zui)低(di)电(dian)(dian)(dian)位(wei)(wei)，②脚(jiao)(jiao)居中(zhong)(zhong)。从图(tu)(tu)中(zhong)(zhong)可以看出(chu)，不论正(zheng)压(ya)还是(shi)负压(ya)，①脚(jiao)(jiao)均为(wei)输(shu)出(chu)端。对(dui)(dui)于78**正(zheng)压(ya)系列(lie)(lie)，输(shu)入是(shi)最(zui)(zui)(zui)高(gao)电(dian)(dian)(dian)位(wei)(wei)，自然(ran)是(shi)①脚(jiao)(jiao)，地端为(wei)最(zui)(zui)(zui)低(di)电(dian)(dian)(dian)位(wei)(wei)，Rr0脚(jiao)(jiao)，如附图(tu)(tu)所示。对(dui)(dui)与l17 9**负压(ya)系列(lie)(lie)，输(shu)入为(wei)最(zui)(zui)(zui)低(di)电(dian)(dian)(dian)位(wei)(wei)，自然(ran)是(shi)0脚(jiao)(jiao)，而地端为(wei)最(zui)(zui)(zui)高(gao)电(dian)(dian)(dian)位(wei)(wei)，即(ji)①脚(jiao)，如附图所示。

三、7812引脚功能

此(ci)外，还(hai)应注意，散热片总(zong)是(shi)和最低电位的第(di)③脚(jiao)相(xiang)连。这样(yang)在78**系(xi)列(lie)中(zhong)(zhong)，散热片和地相(xiang)连接，而在79**系(xi)列(lie)中(zhong)(zhong)，散热片却和输入端相(xiang)连接。

四、7812稳压电源电路图

7812典型应用(yong)电路图：

7812 7812 7812

1、78XX系列集成(cheng)稳压器的典型应(ying)用电(dian)路图(tu)，是一个输(shu)出正5v直(zhi)流(liu)电(dian)压的稳压电(dian)源电(dian)路。IC采(cai)集成(cheng)稳压器7812，CI、C2分别(bie)为输(shu)入端和输(shu)端滤波电(dian)容，RL为负载电(dian)阻。当输(shu)出电(dian)流(liu)较大(da)时(shi)，7812应(ying)配上(shang)散热板。

为(wei)提(ti)高(gao)输出(chu)(chu)电(dian)压(ya)(ya)的应用(yong)电(dian)路。稳(wen)压(ya)(ya)二襁管(guan)VDI串(chuan)接在78XX稳(wen)压(ya)(ya)器2脚与(yu)地之间，可(ke)使输出(chu)(chu)电(dian)压(ya)(ya)Uo得到(dao)一(yi)定的提(ti)高(gao)，输出(chu)(chu)电(dian)压(ya)(ya)Uo为(wei)78XX稳(wen)压(ya)(ya)器输出(chu)(chu)电(dian)压(ya)(ya)与(yu)稳(wen)压(ya)(ya)二极管(guan)VC稳(wen)压(ya)(ya)值(zhi)之和(he)。VD2是输出(chu)(chu)保护二极管(guan)，一(yi)旦输出(chu)(chu)电(dian)压(ya)(ya)低于VDI稳(wen)压(ya)(ya)值(zhi)时，VD2导通，将输出(chu)(chu)电(dian)流旁(pang)路，保护7800稳(wen)压(ya)(ya)器输出(chu)(chu)级不被损坏(huai)。

为输出(chu)电(dian)压(ya)(ya)可在一定(ding)范围(wei)内调节的应用电(dian)路(lu)。由于(yu)R1、RP电(dian)阻网络的作用，使得输出(chu)电(dian)压(ya)(ya)被提(ti)高，提(ti)高的幅度取决于(yu)RP与R1的比值。调节电(dian)位器RP，即可一定(ding)范围(wei)内调节输出(chu)电(dian)压(ya)(ya)。当lP=O时，输出(chu)电(dian)压(ya)(ya)Uo等于(yu)78XX稳(wen)压(ya)(ya)器输出(chu)电(dian)压(ya)(ya)：当RP逐(zhu)步(bu)增大时，Uo也随(sui)之逐(zhu)步(bu)提(ti)高。

为(wei)(wei)扩大(da)输出(chu)电(dian)(dian)流(liu)(liu)的应用电(dian)(dian)路。VT2为(wei)(wei)外接扩流(liu)(liu)率管，VTI为(wei)(wei)推动管，二(er)者为(wei)(wei)达林顿连接。R1为(wei)(wei)偏置(zhi)电(dian)(dian)阻。该电(dian)(dian)路最大(da)输出(chu)电(dian)(dian)流(liu)(liu)取决于VT2的参数。