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大功率MOS管
大功率MOS管构造

本文主(zhu)要是(shi)讲大功率(lv)(lv)(lv)MOS管型(xing)号-大功率(lv)(lv)(lv)MOS管结构、符号等(deng)及(ji)工(gong)作(zuo)原理的(de)(de)详解。大功率(lv)(lv)(lv)MOS管，在一块掺杂浓(nong)度较(jiao)低(di)的(de)(de)P型(xing)半(ban)导(dao)(dao)体硅衬(chen)底(di)上，用半(ban)导(dao)(dao)体光刻、扩散工(gong)艺制(zhi)作(zuo)两个高掺杂浓(nong)度的(de)(de)N+区，并用金属(shu)铝引出两个电极(ji)(ji)(ji)，分别作(zuo)为漏(lou)极(ji)(ji)(ji)D和(he)源极(ji)(ji)(ji)S。然后在漏(lou)极(ji)(ji)(ji)和(he)源极(ji)(ji)(ji)之间(jian)的(de)(de)P型(xing)半(ban)导(dao)(dao)体表面复盖(gai)一层(ceng)(ceng)很(hen)薄(bo)的(de)(de)二氧化硅（Si02）绝(jue)缘(yuan)层(ceng)(ceng)膜(mo)，在再这个绝(jue)缘(yuan)层(ceng)(ceng)膜(mo)上装上一个铝电极(ji)(ji)(ji)，作(zuo)为栅极(ji)(ji)(ji)G。这就(jiu)构成了一个N沟道（NPN型(xing)）增(zeng)强型(xing)MOS管。显然它的(de)(de)栅极(ji)(ji)(ji)和(he)其它电极(ji)(ji)(ji)间(jian)是(shi)绝(jue)缘(yuan)的(de)(de)。下图所(suo)示分别是(shi)它的(de)(de)结构图和(he)代表符号。

同(tong)样用(yong)上(shang)(shang)(shang)述相同(tong)的(de)方(fang)法在一块掺杂浓度较低的(de)N型半导体硅衬底上(shang)(shang)(shang)，用(yong)半导体光刻、扩(kuo)散工艺制作两个高掺杂浓度的(de)P+区，及上(shang)(shang)(shang)述相同(tong)的(de)栅(zha)极制作过程，就制成为一个P沟(gou)道(dao)（PNP型）增强型MOS管。如上(shang)(shang)(shang)图所示(shi)分别是P沟(gou)道(dao)MOS管道(dao)结(jie)构(gou)图和(he)代表符号。

大功率MOS管工作原理

从(cong)下图可以看(kan)出，增强型(xing)MOS管的(de)漏(lou)(lou)极(ji)D和源(yuan)(yuan)极(ji)S之间有(you)(you)两个(ge)背(bei)靠背(bei)的(de)PN结(jie)。当栅-源(yuan)(yuan)电(dian)压VGS=0时，即使加上漏(lou)(lou)-源(yuan)(yuan)电(dian)压VDS，总有(you)(you)一个(ge)PN结(jie)处于反(fan)偏状(zhuang)态，漏(lou)(lou)-源(yuan)(yuan)极(ji)间没有(you)(you)导电(dian)沟道(dao)（没有(you)(you)电(dian)流(liu)流(liu)过(guo)），所以这时漏(lou)(lou)极(ji)电(dian)流(liu)ID=0。

此(ci)时若在栅(zha)(zha)(zha)-源极(ji)(ji)间(jian)加(jia)(jia)上正(zheng)向电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)，图1-3-B所示(shi)，即VGS＞0，则栅(zha)(zha)(zha)极(ji)(ji)和(he)硅(gui)衬(chen)底之间(jian)的(de)(de)(de)(de)SiO2绝(jue)缘(yuan)层(ceng)中便产生一(yi)个栅(zha)(zha)(zha)极(ji)(ji)指向P型(xing)硅(gui)衬(chen)底的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)场，由于氧(yang)化(hua)物层(ceng)是(shi)绝(jue)缘(yuan)的(de)(de)(de)(de)，栅(zha)(zha)(zha)极(ji)(ji)所加(jia)(jia)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)VGS无法(fa)形(xing)成(cheng)(cheng)电(dian)(dian)(dian)(dian)(dian)流(liu)，氧(yang)化(hua)物层(ceng)的(de)(de)(de)(de)两(liang)边(bian)就形(xing)成(cheng)(cheng)了(le)一(yi)个电(dian)(dian)(dian)(dian)(dian)容，VGS等效是(shi)对这(zhei)个电(dian)(dian)(dian)(dian)(dian)容充电(dian)(dian)(dian)(dian)(dian)，并形(xing)成(cheng)(cheng)一(yi)个电(dian)(dian)(dian)(dian)(dian)场，随着VGS逐渐升(sheng)高，受栅(zha)(zha)(zha)极(ji)(ji)正(zheng)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)的(de)(de)(de)(de)吸引，在这(zhei)个电(dian)(dian)(dian)(dian)(dian)容的(de)(de)(de)(de)另一(yi)边(bian)就聚(ju)集大(da)量的(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)子并形(xing)成(cheng)(cheng)了(le)一(yi)个从(cong)漏极(ji)(ji)到源极(ji)(ji)的(de)(de)(de)(de)N型(xing)导(dao)电(dian)(dian)(dian)(dian)(dian)沟道，当(dang)VGS大(da)于管子的(de)(de)(de)(de)开(kai)(kai)启(qi)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)VT（一(yi)般约(yue)为(wei)(wei)(wei) 2V）时，N沟道管开(kai)(kai)始(shi)导(dao)通，形(xing)成(cheng)(cheng)漏极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)流(liu)ID，我们(men)把开(kai)(kai)始(shi)形(xing)成(cheng)(cheng)沟道时的(de)(de)(de)(de)栅(zha)(zha)(zha)-源极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)称为(wei)(wei)(wei)开(kai)(kai)启(qi)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)，一(yi)般用VT表示(shi)。控(kong)制栅(zha)(zha)(zha)极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)VGS的(de)(de)(de)(de)大(da)小(xiao)改(gai)变了(le)电(dian)(dian)(dian)(dian)(dian)场的(de)(de)(de)(de)强弱(ruo)，就可以达到控(kong)制漏极(ji)(ji)电(dian)(dian)(dian)(dian)(dian)流(liu)ID的(de)(de)(de)(de)大(da)小(xiao)的(de)(de)(de)(de)目的(de)(de)(de)(de)，这(zhei)也是(shi)MOS管用电(dian)(dian)(dian)(dian)(dian)场来控(kong)制电(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)一(yi)个重(zhong)要特点，所以也称之为(wei)(wei)(wei)场效应管。

大功率MOS管的电压极性和符号

N沟(gou)道MOS管(guan)的符号，图(tu)中D是(shi)漏极(ji)，S是(shi)源(yuan)极(ji)，G是(shi)栅极(ji)，中间的箭头表(biao)示衬底，如果箭头向里表(biao)示是(shi)N沟(gou)道的MOS管(guan)，箭头向外表(biao)示是(shi)P沟(gou)道的MOS管(guan)。

在实际MOS管(guan)生产的过程中(zhong)衬(chen)底在出厂(chang)前(qian)就和(he)源极(ji)连接，所以在符(fu)(fu)号(hao)的规(gui)则中(zhong)；表示衬(chen)底的箭(jian)头也(ye)必须和(he)源极(ji)相连接，以区别漏极(ji)和(he)源极(ji)。上(shang)图是(shi)P沟道(dao)MOS管(guan)的符(fu)(fu)号(hao)。

大功率MOS管应用电(dian)压(ya)的极(ji)(ji)(ji)(ji)(ji)(ji)性和我们普通的晶(jing)体三(san)(san)极(ji)(ji)(ji)(ji)(ji)(ji)管相(xiang)同，N沟道(dao)的类似(si)NPN晶(jing)体三(san)(san)极(ji)(ji)(ji)(ji)(ji)(ji)管，漏极(ji)(ji)(ji)(ji)(ji)(ji)D接正极(ji)(ji)(ji)(ji)(ji)(ji)，源(yuan)极(ji)(ji)(ji)(ji)(ji)(ji)S接负极(ji)(ji)(ji)(ji)(ji)(ji)，栅极(ji)(ji)(ji)(ji)(ji)(ji)G正电(dian)压(ya)时(shi)导电(dian)沟道(dao)建(jian)立，N沟道(dao)MOS管开始工(gong)作,如下图(tu)(tu)所(suo)示。同样P道(dao)的类似(si)PNP晶(jing)体三(san)(san)极(ji)(ji)(ji)(ji)(ji)(ji)管，漏极(ji)(ji)(ji)(ji)(ji)(ji)D接负极(ji)(ji)(ji)(ji)(ji)(ji)，源(yuan)极(ji)(ji)(ji)(ji)(ji)(ji)S接正极(ji)(ji)(ji)(ji)(ji)(ji)，栅极(ji)(ji)(ji)(ji)(ji)(ji)G负电(dian)压(ya)时(shi)，导电(dian)沟道(dao)建(jian)立，P沟道(dao)MOS管开始工(gong)作,如下图(tu)(tu)所(suo)示。

大功率MOS管开关电路

实例应用电(dian)路分析

初步的(de)(de)了(le)解了(le)以上的(de)(de)关于大功率MOS管的(de)(de)一些知识后，一般的(de)(de)就可以简单的(de)(de)分析，采用MOS管开关电(dian)源的(de)(de)电(dian)路了(le)。

1、 三星等离子V2屏开关电(dian)源PFC部分激(ji)励电(dian)路分析(xi)；

如(ru)下(xia)图(tu)1所示是(shi)三星V2屏(ping)开关电源，PFC电源部(bu)分电原(yuan)理图(tu)，图(tu)2所示是(shi)其(qi)等(deng)效(xiao)电路框图(tu)。

图1

图2

图(tu)1所示(shi)；是(shi)(shi)(shi)(shi)三(san)星(xing)V2屏等(deng)离子开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)PFC激励(li)部(bu)分。从图(tu)中(zhong)(zhong)可以看出(chu)；这是(shi)(shi)(shi)(shi)一个并联(lian)开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)L1是(shi)(shi)(shi)(shi)储(chu)能电(dian)(dian)(dian)(dian)(dian)(dian)(dian)感，D10是(shi)(shi)(shi)(shi)这个开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)(de)(de)整(zheng)流(liu)二(er)极(ji)(ji)(ji)管(guan)(guan)，Q1、Q2是(shi)(shi)(shi)(shi)开关(guan)管(guan)(guan)，为了保证PFC开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)有(you)足够的(de)(de)(de)(de)功率输出(chu)，采用了两(liang)只MOS管(guan)(guan)Q1、Q2并联(lian)应(ying)用（图(tu)2所示(shi)；是(shi)(shi)(shi)(shi)该(gai)并联(lian)开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)等(deng)效电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路图(tu)，图(tu)中(zhong)(zhong)可以看出(chu)该(gai)并联(lian)开关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)是(shi)(shi)(shi)(shi)加在(zai)整(zheng)流(liu)桥(qiao)堆和(he)(he)(he)滤波(bo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)容C5之(zhi)间的(de)(de)(de)(de)），图(tu)中(zhong)(zhong)Q3、Q4是(shi)(shi)(shi)(shi)灌流(liu)激励(li)管(guan)(guan)，Q3、Q4的(de)(de)(de)(de)基极(ji)(ji)(ji)输入开关(guan)激励(li)信(xin)号， VCC-S-R是(shi)(shi)(shi)(shi)Q3、Q4的(de)(de)(de)(de)VCC供(gong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(22.5V)。两(liang)只开关(guan)管(guan)(guan)Q1、Q2的(de)(de)(de)(de)栅极(ji)(ji)(ji)分别有(you)各(ge)自(zi)的(de)(de)(de)(de)充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)限流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)和(he)(he)(he)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)二(er)极(ji)(ji)(ji)管(guan)(guan)，R16是(shi)(shi)(shi)(shi)Q2的(de)(de)(de)(de)在(zai)激烈(lie)信(xin)号为正半周时的(de)(de)(de)(de)对Q2栅极(ji)(ji)(ji)等(deng)效电(dian)(dian)(dian)(dian)(dian)(dian)(dian)容充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)限流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)，D7是(shi)(shi)(shi)(shi)Q2在(zai)激烈(lie)信(xin)号为负半周时的(de)(de)(de)(de)Q2栅极(ji)(ji)(ji)等(deng)效电(dian)(dian)(dian)(dian)(dian)(dian)(dian)容放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)二(er)极(ji)(ji)(ji)管(guan)(guan)，同样R14、D6则是(shi)(shi)(shi)(shi)Q1的(de)(de)(de)(de)充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)限流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)和(he)(he)(he)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)二(er)极(ji)(ji)(ji)管(guan)(guan)。R17和(he)(he)(he)R18是(shi)(shi)(shi)(shi)Q1和(he)(he)(he)Q2的(de)(de)(de)(de)关(guan)机栅极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷泄放电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)。D9是(shi)(shi)(shi)(shi)开机瞬间浪(lang)涌电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)分流(liu)二(er)极(ji)(ji)(ji)管(guan)(guan)。

大功率MOS管特性

上述大(da)(da)功率MOS管工作原(yuan)理中可以(yi)看出，MOS管的(de)(de)栅(zha)(zha)极(ji)(ji)G和(he)源极(ji)(ji)S之间(jian)是绝缘的(de)(de)，由于Sio2绝缘层的(de)(de)存在(zai)(zai)，在(zai)(zai)栅(zha)(zha)极(ji)(ji)G和(he)源极(ji)(ji)S之间(jian)等效是一个电(dian)容(rong)存在(zai)(zai)，电(dian)压(ya)(ya)VGS产(chan)生(sheng)(sheng)电(dian)场从而导致(zhi)源极(ji)(ji)-漏(lou)极(ji)(ji)电(dian)流的(de)(de)产(chan)生(sheng)(sheng)。此时的(de)(de)栅(zha)(zha)极(ji)(ji)电(dian)压(ya)(ya)VGS决定了漏(lou)极(ji)(ji)电(dian)流的(de)(de)大(da)(da)小(xiao)，控(kong)制栅(zha)(zha)极(ji)(ji)电(dian)压(ya)(ya)VGS的(de)(de)大(da)(da)小(xiao)就可以(yi)控(kong)制漏(lou)极(ji)(ji)电(dian)流ID的(de)(de)大(da)(da)小(xiao)。这就可以(yi)得出如下结论：

1） MOS管是一个由改(gai)变电压来控制电流的器件(jian)，所以(yi)是电压器件(jian)。

2） MOS管道输入特(te)(te)性为容性特(te)(te)性，所以输入阻抗极高。

大功率MOS管型号