如何选(xuan)择mos管(guan)-教你用四种方法合理选(xuan)择mos管(guan)-KIA MOS管(guan)
信(xin)息来源：本站 日期：2018-09-12
正确选择(ze)MOS管是(shi)很重要的(de)一个环节，MOS管选择(ze)不好有可(ke)能影响到(dao)整个电(dian)路(lu)的(de)效率(lv)和成本，了解不同的(de)MOS管部件的(de)细微差别(bie)及(ji)不同开关电(dian)路(lu)中的(de)应(ying)力能够帮助工程师(shi)避免(mian)诸多问题，下面我(wo)们来学习下如何选择(ze)mos管正确方(fang)法。
为设计选择正确器件(jian)的第一步是决定采用N沟(gou)道(dao)还是P沟(gou)道(dao)MOS管(guan)(guan)。在(zai)(zai)典型的功(gong)率应用中(zhong)，当一个MOS管(guan)(guan)接(jie)(jie)地，而负载(zai)连(lian)接(jie)(jie)到(dao)干线电压(ya)上(shang)时，该MOS管(guan)(guan)就构成(cheng)了低压(ya)侧开关。在(zai)(zai)低压(ya)侧开关中(zhong)，应采用N沟(gou)道(dao)MOS管(guan)(guan)，这是出于(yu)对关闭或(huo)导通器件(jian)所(suo)需(xu)电压(ya)的考虑。当MOS管(guan)(guan)连(lian)接(jie)(jie)到(dao)总线及负载(zai)接(jie)(jie)地时，就要用高压(ya)侧开关。通常会(hui)在(zai)(zai)这个拓(tuo)扑中(zhong)采用P沟(gou)道(dao)MOS管(guan)(guan)，这也是出于(yu)对电压(ya)驱动的考虑。
要选择(ze)适合(he)应(ying)用(yong)(yong)的(de)(de)(de)器(qi)件，必(bi)(bi)须确(que)定(ding)驱动器(qi)件所(suo)需(xu)的(de)(de)(de)电(dian)(dian)(dian)压(ya)，以及在(zai)设(she)(she)(she)(she)计中最(zui)简易执行的(de)(de)(de)方法。下一步(bu)是(shi)确(que)定(ding)所(suo)需(xu)的(de)(de)(de)额(e)定(ding)电(dian)(dian)(dian)压(ya)，或者器(qi)件所(suo)能(neng)(neng)承受的(de)(de)(de)最(zui)大电(dian)(dian)(dian)压(ya)。额(e)定(ding)电(dian)(dian)(dian)压(ya)越大，器(qi)件的(de)(de)(de)成本就(jiu)越高(gao)。根据实践经验，额(e)定(ding)电(dian)(dian)(dian)压(ya)应(ying)当大于干线电(dian)(dian)(dian)压(ya)或总(zong)线电(dian)(dian)(dian)压(ya)。这(zhei)样(yang)才(cai)能(neng)(neng)提供足够的(de)(de)(de)保护(hu)，使MOS管(guan)不会(hui)失效。就(jiu)选择(ze)MOS管(guan)而言，必(bi)(bi)须确(que)定(ding)漏极至源极间可能(neng)(neng)承受的(de)(de)(de)最(zui)大电(dian)(dian)(dian)压(ya)，即最(zui)大VDS。知道MOS管(guan)能(neng)(neng)承受的(de)(de)(de)最(zui)大电(dian)(dian)(dian)压(ya)会(hui)随(sui)温度而变化这(zhei)点十分重要。设(she)(she)(she)(she)计人(ren)员必(bi)(bi)须在(zai)整(zheng)个(ge)工作温度范围(wei)(wei)内测试电(dian)(dian)(dian)压(ya)的(de)(de)(de)变化范围(wei)(wei)。额(e)定(ding)电(dian)(dian)(dian)压(ya)必(bi)(bi)须有足够的(de)(de)(de)余(yu)量覆盖这(zhei)个(ge)变化范围(wei)(wei)，确(que)保电(dian)(dian)(dian)路不会(hui)失效。设(she)(she)(she)(she)计工程师需(xu)要考虑的(de)(de)(de)其他(ta)安全(quan)因(yin)素包括(kuo)由(you)开关电(dian)(dian)(dian)子设(she)(she)(she)(she)备(bei)(bei)(如电(dian)(dian)(dian)机(ji)或变压(ya)器(qi))诱发的(de)(de)(de)电(dian)(dian)(dian)压(ya)瞬变。不同(tong)应(ying)用(yong)(yong)的(de)(de)(de)额(e)定(ding)电(dian)(dian)(dian)压(ya)也有所(suo)不同(tong)；通常，便携式设(she)(she)(she)(she)备(bei)(bei)为20V、FPGA电(dian)(dian)(dian)源为20～30V、85～220VAC应(ying)用(yong)(yong)为450～600V。
第二步是(shi)选择(ze)MOS管的额(e)定(ding)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)。视(shi)电(dian)(dian)(dian)(dian)路结构而定(ding)，该(gai)额(e)定(ding)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)应是(shi)负载在(zai)所有情况(kuang)下(xia)能够承受(shou)(shou)的最(zui)大电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)。与电(dian)(dian)(dian)(dian)压的情况(kuang)相似，设计人员必须(xu)确保所选的MOS管能承受(shou)(shou)这个(ge)额(e)定(ding)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，即使在(zai)系统产生尖峰(feng)(feng)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)时。两个(ge)考虑(lv)的电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)情况(kuang)是(shi)连(lian)续模(mo)式和脉(mai)冲(chong)尖峰(feng)(feng)。在(zai)连(lian)续导通模(mo)式下(xia)，MOS管处于(yu)稳态，此(ci)时电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)连(lian)续通过器(qi)(qi)件。脉(mai)冲(chong)尖峰(feng)(feng)是(shi)指有大量(liang)电(dian)(dian)(dian)(dian)涌(或(huo)尖峰(feng)(feng)电(dian)(dian)(dian)(dian)流(liu)(liu)(liu))流(liu)(liu)(liu)过器(qi)(qi)件。一旦确定(ding)了(le)这些条件下(xia)的最(zui)大电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，只需直(zhi)接选择(ze)能承受(shou)(shou)这个(ge)最(zui)大电(dian)(dian)(dian)(dian)流(liu)(liu)(liu)的器(qi)(qi)件便可。
选好额定电(dian)(dian)流后，还必须计算导通(tong)损(sun)耗(hao)(hao)。在实际(ji)情况下，MOS管(guan)并不(bu)是(shi)(shi)理(li)想的(de)器(qi)件，因(yin)(yin)为在导电(dian)(dian)过程中会(hui)有(you)电(dian)(dian)能损(sun)耗(hao)(hao)，这称之(zhi)(zhi)为导通(tong)损(sun)耗(hao)(hao)。MOS管(guan)在“导通(tong)”时就(jiu)像一个可(ke)(ke)变(bian)电(dian)(dian)阻(zu)，由器(qi)件的(de)RDS(ON)所确定，并随(sui)温(wen)度而(er)显著(zhu)变(bian)化(hua)(hua)。器(qi)件的(de)功(gong)率(lv)耗(hao)(hao)损(sun)可(ke)(ke)由Iload2×RDS(ON)计算，由于导通(tong)电(dian)(dian)阻(zu)随(sui)温(wen)度变(bian)化(hua)(hua)，因(yin)(yin)此(ci)功(gong)率(lv)耗(hao)(hao)损(sun)也会(hui)随(sui)之(zhi)(zhi)按比例(li)变(bian)化(hua)(hua)。对MOS管(guan)施加(jia)的(de)电(dian)(dian)压VGS越高，RDS(ON)就(jiu)会(hui)越小；反之(zhi)(zhi)RDS(ON)就(jiu)会(hui)越高。对系统(tong)设计人员来说，这就(jiu)是(shi)(shi)取决(jue)于系统(tong)电(dian)(dian)压而(er)需(xu)要(yao)折中权衡的(de)地方。对便携(xie)式设计来说，采用较(jiao)(jiao)低的(de)电(dian)(dian)压比较(jiao)(jiao)容易(较(jiao)(jiao)为普遍)，而(er)对于工(gong)业设计，可(ke)(ke)采用较(jiao)(jiao)高的(de)电(dian)(dian)压。注(zhu)意RDS(ON)电(dian)(dian)阻(zu)会(hui)随(sui)着电(dian)(dian)流轻微上升(sheng)。关于RDS(ON)电(dian)(dian)阻(zu)的(de)各种电(dian)(dian)气参数变(bian)化(hua)(hua)可(ke)(ke)在制造商提供(gong)的(de)技术资(zi)料表中查(cha)到。
技(ji)(ji)(ji)术对(dui)(dui)器件的特性(xing)有(you)(you)(you)着重(zhong)大(da)影响(xiang)，因为有(you)(you)(you)些技(ji)(ji)(ji)术在(zai)提(ti)高最大(da)VDS时往(wang)往(wang)会使RDS(ON)增大(da)。对(dui)(dui)于这样的技(ji)(ji)(ji)术，如果打算降低(di)VDS和RDS(ON)，那么(me)就得增加晶片尺(chi)寸(cun)，从(cong)而增加与之配套的封装尺(chi)寸(cun)及相关的开发成本。业(ye)界现有(you)(you)(you)好(hao)几种试(shi)图(tu)控制晶片尺(chi)寸(cun)增加的技(ji)(ji)(ji)术，其中最主(zhu)要的是(shi)沟道(dao)和电荷平(ping)衡技(ji)(ji)(ji)术。
在沟道技术(shu)中，晶(jing)片中嵌入了一个深沟，通常是为(wei)低电(dian)压预留的(de)(de)(de)，用于降(jiang)低导(dao)(dao)通电(dian)阻RDS(ON)。为(wei)了减(jian)少最大(da)VDS对(dui)RDS(ON)的(de)(de)(de)影(ying)响，开发(fa)过程中采用了外延生长柱(zhu)/蚀刻柱(zhu)工艺(yi)。例(li)如(ru)，飞兆半导(dao)(dao)体(ti)开发(fa)了称为(wei)SupeRFET的(de)(de)(de)技术(shu)，针对(dui)RDS(ON)的(de)(de)(de)降(jiang)低而增(zeng)加了额(e)外的(de)(de)(de)制造步骤。这种对(dui)RDS(ON)的(de)(de)(de)关(guan)(guan)注(zhu)十分重(zhong)要，因(yin)为(wei)当(dang)标准MOSFET的(de)(de)(de)击(ji)穿电(dian)压升高时(shi)，RDS(ON)会随之呈指数级增(zeng)加，并且导(dao)(dao)致晶(jing)片尺(chi)寸(cun)增(zeng)大(da)。SuperFET工艺(yi)将RDS(ON)与晶(jing)片尺(chi)寸(cun)间的(de)(de)(de)指数关(guan)(guan)系变成了线性关(guan)(guan)系。这样，SuperFET器(qi)件便可在小(xiao)晶(jing)片尺(chi)寸(cun)，甚至在击(ji)穿电(dian)压达到600V的(de)(de)(de)情况下，实现理想的(de)(de)(de)低RDS(ON)。结果是晶(jing)片尺(chi)寸(cun)可减(jian)小(xiao)达35%。而对(dui)于最终(zhong)用户来说，这意味着封装尺(chi)寸(cun)的(de)(de)(de)大(da)幅减(jian)小(xiao)。
如(ru)何选择mos管(guan)的(de)(de)下一步是计算系统(tong)的(de)(de)散热(re)要求(qiu)。设(she)计人员必须考(kao)虑两种(zhong)不同的(de)(de)情况(kuang)，即(ji)最(zui)(zui)坏情况(kuang)和(he)真实(shi)情况(kuang)。建(jian)议采用(yong)针对最(zui)(zui)坏情况(kuang)的(de)(de)计算结(jie)(jie)果，因为这个结(jie)(jie)果提供更大的(de)(de)安全余量，能确保系统(tong)不会失效。在MOS管(guan)的(de)(de)资料表上还有一些需要注意的(de)(de)测量数据；比如(ru)封装器件的(de)(de)半导体(ti)结(jie)(jie)与环(huan)境(jing)之间的(de)(de)热(re)阻，以(yi)及最(zui)(zui)大的(de)(de)结(jie)(jie)温。
器件(jian)的(de)(de)(de)结温(wen)(wen)(wen)等于最大(da)(da)环境温(wen)(wen)(wen)度加(jia)上热阻与功(gong)率耗(hao)散的(de)(de)(de)乘积(结温(wen)(wen)(wen)=最大(da)(da)环境温(wen)(wen)(wen)度+[热阻×功(gong)率耗(hao)散])。根据这个方(fang)程可(ke)解出系(xi)统的(de)(de)(de)最大(da)(da)功(gong)率耗(hao)散，即按定义相等于I2×RDS(ON)。由于设(she)计人(ren)员已确(que)定将要(yao)通过器件(jian)的(de)(de)(de)最大(da)(da)电流(liu)，因此可(ke)以计算出不同温(wen)(wen)(wen)度下的(de)(de)(de)RDS(ON)。值得注意的(de)(de)(de)是，在处理简单热模型(xing)时，设(she)计人(ren)员还必须考(kao)虑半导体结/器件(jian)外壳(qiao)及外壳(qiao)/环境的(de)(de)(de)热容量；即要(yao)求(qiu)印刷电路板和封装(zhuang)不会(hui)立即升温(wen)(wen)(wen)。
雪(xue)(xue)崩(beng)(beng)击穿是指半导体(ti)器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)上的(de)反(fan)向电(dian)压超(chao)过最大值，并形成(cheng)强电(dian)场使器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)内电(dian)流增加(jia)。该电(dian)流将耗散功率，使器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)的(de)温度升高，而(er)且有可能损(sun)坏器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)。半导体(ti)公司(si)都会对(dui)器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)进(jin)行雪(xue)(xue)崩(beng)(beng)测试(shi)，计(ji)(ji)算其雪(xue)(xue)崩(beng)(beng)电(dian)压，或对(dui)器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)的(de)稳健性(xing)进(jin)行测试(shi)。计(ji)(ji)算额定雪(xue)(xue)崩(beng)(beng)电(dian)压有两种方法；一(yi)是统计(ji)(ji)法，另一(yi)是热(re)计(ji)(ji)算。而(er)热(re)计(ji)(ji)算因(yin)为较为实(shi)用而(er)得到广泛采用。除计(ji)(ji)算外，技术对(dui)雪(xue)(xue)崩(beng)(beng)效应也有很大影响(xiang)。例如，晶片(pian)尺寸的(de)增加(jia)会提(ti)高抗雪(xue)(xue)崩(beng)(beng)能力，最终(zhong)提(ti)高器(qi)(qi)(qi)件(jian)(jian)(jian)(jian)的(de)稳健性(xing)。对(dui)最终(zhong)用户而(er)言，这意味着要在系(xi)统中采用更大的(de)封装件(jian)(jian)(jian)(jian)。
如何选择mos管(guan)的最后一步(bu)是决(jue)定MOS管(guan)的开(kai)(kai)(kai)关(guan)性(xing)能(neng)。影响开(kai)(kai)(kai)关(guan)性(xing)能(neng)的参数有很(hen)多，但最重要的是栅极/漏(lou)极、栅极/ 源(yuan)极及漏(lou)极/源(yuan)极电容。这(zhei)些电容会在器件中产生开(kai)(kai)(kai)关(guan)损耗(hao)(hao)(hao)，因为(wei)在每次开(kai)(kai)(kai)关(guan)时都(dou)要对它(ta)们(men)充(chong)电。MOS管(guan)的开(kai)(kai)(kai)关(guan)速度因此被降低，器件效率也(ye)下降。为(wei)计算开(kai)(kai)(kai)关(guan)过(guo)程中器件的总损耗(hao)(hao)(hao)，设计人(ren)员必须计算开(kai)(kai)(kai)通过(guo)程中的损耗(hao)(hao)(hao)(Eon)和关(guan)闭过(guo)程中的损耗(hao)(hao)(hao)(Eoff)。MOSFET开(kai)(kai)(kai)关(guan)的总功(gong)率可(ke)用(yong)如下方程表达：Psw=(Eon+Eoff)×开(kai)(kai)(kai)关(guan)频(pin)率。而栅极电荷(Qgd)对开(kai)(kai)(kai)关(guan)性(xing)能(neng)的影响最大。
在了解如何选择mos管(guan)后，接下(xia)来(lai)(lai)会讲到mos管(guan)的(de)(de)(de)导(dao)(dao)通(tong)条件(jian)及导(dao)(dao)通(tong)过程，导(dao)(dao)通(tong)与截止由(you)栅源(yuan)(yuan)电(dian)压来(lai)(lai)控制，对于增强(qiang)型(xing)(xing)场效应管(guan)来(lai)(lai)说，N沟道(dao)(dao)的(de)(de)(de)管(guan)子加正向电(dian)压即(ji)导(dao)(dao)通(tong)，P沟道(dao)(dao)的(de)(de)(de)管(guan)子则加反向电(dian)压。一般2V～4V就可以了。但(dan)是(shi)，场效应管(guan)分(fen)为增强(qiang)型(xing)(xing)（常开型(xing)(xing)）和耗尽型(xing)(xing)（常闭型(xing)(xing)），增强(qiang)型(xing)(xing)的(de)(de)(de)管(guan)子是(shi)需(xu)要加电(dian)压才能导(dao)(dao)通(tong)的(de)(de)(de)，而(er)耗尽型(xing)(xing)管(guan)子本来(lai)(lai)就处于导(dao)(dao)通(tong)状态，加栅源(yuan)(yuan)电(dian)压是(shi)为了使其(qi)截止。
开关只有(you)两种状(zhuang)态(tai)通和断，三极管(guan)和场效应管(guan)工作有(you)三种状(zhuang)态(tai)：
1、截止；
2、线性放大(da)；
3、饱和（基极电流继续增加而集电极电流不再(zai)增加）；
使(shi)晶(jing)(jing)体(ti)管(guan)只工作在1和(he)3状态(tai)的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)称之为开关电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)，一般(ban)以(yi)晶(jing)(jing)体(ti)管(guan)截止，集电(dian)(dian)(dian)(dian)(dian)(dian)(dian)极(ji)不吸收(shou)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)表(biao)示(shi)关；以(yi)晶(jing)(jing)体(ti)管(guan)饱和(he)，发射(she)极(ji)和(he)集电(dian)(dian)(dian)(dian)(dian)(dian)(dian)极(ji)之间(jian)的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压差接近于0V时(shi)表(biao)示(shi)开。开关电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)用(yong)于数(shu)字(zi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)时(shi)，输出电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位接近0V时(shi)表(biao)示(shi)0，输出电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位接近电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压时(shi)表(biao)示(shi)1。所(suo)以(yi)数(shu)字(zi)集成电(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)内部的(de)(de)(de)晶(jing)(jing)体(ti)管(guan)都工作在开关状态(tai)。 场效应管(guan)按沟道(dao)分可分为Ｎ沟道(dao)和(he)Ｐ沟道(dao)管(guan)（在符(fu)号图中可看到(dao)中间(jian)的(de)(de)(de)箭(jian)头方向(xiang)不一样）。
按材料(liao)分可分为结型(xing)管(guan)(guan)(guan)(guan)(guan)和(he)绝(jue)缘(yuan)栅型(xing)管(guan)(guan)(guan)(guan)(guan)，绝(jue)缘(yuan)栅型(xing)又分为耗尽(jin)(jin)型(xing)和(he)增(zeng)强型(xing)，一般(ban)主板上(shang)大多是(shi)绝(jue)缘(yuan)栅型(xing)管(guan)(guan)(guan)(guan)(guan)简称MOS管(guan)(guan)(guan)(guan)(guan)，并且大多采用(yong)(yong)增(zeng)强型(xing)的(de)Ｎ沟道，其次是(shi)增(zeng)强型(xing)的(de)Ｐ沟道，结型(xing)管(guan)(guan)(guan)(guan)(guan)和(he)耗尽(jin)(jin)型(xing)管(guan)(guan)(guan)(guan)(guan)几乎不(bu)用(yong)(yong)。场(chang)效(xiao)(xiao)应(ying)晶(jing)体管(guan)(guan)(guan)(guan)(guan)（Field Effect Transistor缩写(FET)）简称场(chang)效(xiao)(xiao)应(ying)管(guan)(guan)(guan)(guan)(guan).由多数(shu)载流(liu)(liu)(liu)子参与导(dao)电(dian),也(ye)称为单极型(xing)晶(jing)体管(guan)(guan)(guan)(guan)(guan).它(ta)属(shu)于电(dian)压控(kong)制型(xing)半导(dao)体器件(jian).场(chang)效(xiao)(xiao)应(ying)管(guan)(guan)(guan)(guan)(guan)是(shi)利用(yong)(yong)多数(shu)载流(liu)(liu)(liu)子导(dao)电(dian),所以称之为单极型(xing)器件(jian),而(er)晶(jing)体管(guan)(guan)(guan)(guan)(guan)是(shi)即有(you)多数(shu)载流(liu)(liu)(liu)子,也(ye)利用(yong)(yong)少数(shu)载流(liu)(liu)(liu)子导(dao)电(dian),被称之为双极型(xing)器件(jian).有(you)些场(chang)效(xiao)(xiao)应(ying)管(guan)(guan)(guan)(guan)(guan)的(de)源极和(he)漏(lou)极可以互换使用(yong)(yong),栅压也(ye)可正可负,灵活性比(bi)晶(jing)体管(guan)(guan)(guan)(guan)(guan)好。
导通时序可分为to~t1、t1~t2、 t2~t3 、t3~t4四个时间(jian)段(duan)，这四个时间(jian)段(duan)有不同的等效电路。
1）t0-t1：C GS1 开始(shi)充电，栅极电压还没(mei)有(you)到(dao)达V GS（th），导电沟道没(mei)有(you)形成，MOSFET仍处于关闭(bi)状(zhuang)态。
2）[t1-t2]区间, GS间电(dian)压到(dao)达Vgs（th），DS间导电(dian)沟道开(kai)(kai)始形成(cheng)，MOSFET开(kai)(kai)启，DS电(dian)流增(zeng)加到(dao)ID, Cgs2 迅速充(chong)电(dian)，Vgs由(you)Vgs（th）指(zhi)数增(zeng)长(zhang)到(dao)Va。
3）[t2-t3]区(qu)间,MOSFET的DS电压降至与Vgs相同,产(chan)生Millier效应，Cgd电容(rong)大大增(zeng)(zeng)加,栅极电流持(chi)续流过，由于C gd 电容(rong)急剧增(zeng)(zeng)大，抑制了栅极电压对(dui)Cgs 的充电,从而(er)使得Vgs 近乎(hu)水平状态(tai)，Cgd 电容(rong)上(shang)电压增(zeng)(zeng)加,而(er)DS电容(rong)上(shang)的电压继续减(jian)小(xiao)。
4）[t3-t4]区(qu)间,至t3时(shi)刻(ke),MOSFET的DS电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)降至饱和导(dao)通时(shi)的电(dian)(dian)(dian)(dian)(dian)压(ya)(ya),Millier效应影响变小(xiao)，Cgd 电(dian)(dian)(dian)(dian)(dian)容变小(xiao)并和Cgs 电(dian)(dian)(dian)(dian)(dian)容一起由外部驱动(dong)电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)充电(dian)(dian)(dian)(dian)(dian), Cgs 电(dian)(dian)(dian)(dian)(dian)容的电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)上(shang)升,至t4时(shi)刻(ke)为止(zhi).此时(shi)C gs 电(dian)(dian)(dian)(dian)(dian)容电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)已达稳(wen)态,DS间电(dian)(dian)(dian)(dian)(dian)压(ya)(ya)也(ye)达最(zui)小(xiao)，MOSFET完全开启。
联系方式：邹先生
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