第一种：mos管开关电路图

MOS管的开关特性

静态特性

MOS管(guan)作为(wei)开关元件(jian)，同样(yang)是(shi)工作在截止或导通(tong)两种(zhong)状态。由于MOS管(guan)是(shi)电压控制元件(jian)，所(suo)以(yi)主(zhu)要由栅源电压uGS决定(ding)其工作状态。

工作特性如下：

※uGS<开(kai)(kai)启电(dian)压UT:MOS管(guan)工作在(zai)截(jie)止区，漏源电(dian)流iDS基(ji)本(ben)为(wei)0,输出(chu)电(dian)压uDS≈UDD,MOS管(guan)处于“断开(kai)(kai)”状(zhuang)态，其等效电(dian)路如下图所示。

※ uGS>开启电(dian)(dian)压UT:MOS管工作(zuo)在导通(tong)区，漏源电(dian)(dian)流iDS=UDD/(RD+rDS)。其中，rDS为MOS管导通(tong)时的(de)漏源电(dian)(dian)阻。输出(chu)电(dian)(dian)压UDS=UDD·rDS/(RD+rDS)，如果rDS《RD,则(ze)uDS≈0V,MOS管处于“接通(tong)”状态，其等效电(dian)(dian)路如上(shang)图(c)所(suo)示。

动态特性

MOS管(guan)(guan)在导通(tong)与截止(zhi)两(liang)种状态(tai)发生转换时(shi)同样存在过渡过程，但其(qi)动(dong)态(tai)特性(xing)主要取决于与电(dian)路有(you)关的杂(za)散电(dian)容(rong)充、放电(dian)所需的时(shi)间，而管(guan)(guan)子本身导通(tong)和截止(zhi)时(shi)电(dian)荷(he)积累和消散的时(shi)间是很小的。下图 (a)和(b)分(fen)别(bie)给(ji)出了一个NMOS管(guan)(guan)组成(cheng)的电(dian)路及(ji)其(qi)动(dong)态(tai)特性(xing)示意图。

（NMOS管(guan)动态(tai)特性(xing)示意图）

当输入电(dian)(dian)(dian)压ui由(you)高变(bian)低，MOS管由(you)导(dao)通(tong)(tong)(tong)(tong)状(zhuang)(zhuang)态(tai)转(zhuan)换(huan)(huan)为(wei)截止(zhi)(zhi)状(zhuang)(zhuang)态(tai)时(shi)，电(dian)(dian)(dian)源UDD通(tong)(tong)(tong)(tong)过RD向杂(za)散(san)电(dian)(dian)(dian)容CL充(chong)(chong)电(dian)(dian)(dian)，充(chong)(chong)电(dian)(dian)(dian)时(shi)间(jian)(jian)(jian)常(chang)(chang)数(shu)τ1=RDCL.所以，输出电(dian)(dian)(dian)压uo要通(tong)(tong)(tong)(tong)过一定(ding)延时(shi)才由(you)低电(dian)(dian)(dian)平变(bian)为(wei)高电(dian)(dian)(dian)平;当输入电(dian)(dian)(dian)压ui由(you)低变(bian)高，MOS管由(you)截止(zhi)(zhi)状(zhuang)(zhuang)态(tai)转(zhuan)换(huan)(huan)为(wei)导(dao)通(tong)(tong)(tong)(tong)状(zhuang)(zhuang)态(tai)时(shi)，杂(za)散(san)电(dian)(dian)(dian)容CL上的电(dian)(dian)(dian)荷通(tong)(tong)(tong)(tong)过rDS进(jin)行放电(dian)(dian)(dian)，其放电(dian)(dian)(dian)时(shi)间(jian)(jian)(jian)常(chang)(chang)数(shu)τ2≈rDSCL.可见，输出电(dian)(dian)(dian)压Uo也要经过一定(ding)延时(shi)才能(neng)转(zhuan)变(bian)成低电(dian)(dian)(dian)平。但因为(wei)rDS比RD小得多，所以，由(you)截止(zhi)(zhi)到导(dao)通(tong)(tong)(tong)(tong)的转(zhuan)换(huan)(huan)时(shi)间(jian)(jian)(jian)比由(you)导(dao)通(tong)(tong)(tong)(tong)到截止(zhi)(zhi)的转(zhuan)换(huan)(huan)时(shi)间(jian)(jian)(jian)要短。

由于MOS管(guan)(guan)(guan)(guan)导通时(shi)的(de)漏(lou)源(yuan)电(dian)(dian)(dian)阻(zu)(zu)rDS比(bi)晶体三(san)极(ji)管(guan)(guan)(guan)(guan)的(de)饱和(he)电(dian)(dian)(dian)阻(zu)(zu)rCES要大得(de)多，漏(lou)极(ji)外接电(dian)(dian)(dian)阻(zu)(zu)RD也比(bi)晶体管(guan)(guan)(guan)(guan)集(ji)电(dian)(dian)(dian)极(ji)电(dian)(dian)(dian)阻(zu)(zu)RC大，所以，MOS管(guan)(guan)(guan)(guan)的(de)充、放(fang)电(dian)(dian)(dian)时(shi)间较长，使MOS管(guan)(guan)(guan)(guan)的(de)开关速度(du)比(bi)晶体三(san)极(ji)管(guan)(guan)(guan)(guan)的(de)开关速度(du)低。不过，在CMOS电(dian)(dian)(dian)路(lu)中，由于充电(dian)(dian)(dian)电(dian)(dian)(dian)路(lu)和(he)放(fang)电(dian)(dian)(dian)电(dian)(dian)(dian)路(lu)都是低阻(zu)(zu)电(dian)(dian)(dian)路(lu)，因此，其(qi)充、放(fang)电(dian)(dian)(dian)过程(cheng)都比(bi)较快(kuai)，从而使CMOS电(dian)(dian)(dian)路(lu)有较高的(de)开关速度(du)。

MOS管导通特性

导通的(de)意(yi)思是作为开关，相当于(yu)开关闭合(he)。

NMOS的特性，Vgs大于一定(ding)的值就会导通，适合用于源极接地时的情况(低端驱动)，只要栅极电压达到4V或10V就可以了。

PMOS的特性，Vgs小(xiao)于(yu)(yu)一定的值就会(hui)导通(tong)，适合用于(yu)(yu)源极接VCC时(shi)的情况(高端(duan)(duan)驱动(dong)(dong))。但(dan)(dan)是，虽然PMOS可以很(hen)方便地用作高端(duan)(duan)驱动(dong)(dong)，但(dan)(dan)由于(yu)(yu)导通(tong)电(dian)阻大(da)，价格贵，替(ti)换种类少等原因，在高端(duan)(duan)驱动(dong)(dong)中，通(tong)常还(hai)是使(shi)用NMOS.

MOS开关管损失

不(bu)管(guan)(guan)是NMOS还是PMOS,导(dao)通(tong)(tong)后都有导(dao)通(tong)(tong)电阻存(cun)在，这(zhei)样电流就会(hui)(hui)在这(zhei)个电阻上消耗能量(liang)，这(zhei)部分消耗的(de)(de)(de)能量(liang)叫做导(dao)通(tong)(tong)损耗。选择导(dao)通(tong)(tong)电阻小的(de)(de)(de)MOS管(guan)(guan)会(hui)(hui)减小导(dao)通(tong)(tong)损耗。现在的(de)(de)(de)小功率MOS管(guan)(guan)导(dao)通(tong)(tong)电阻一般在几十毫欧左右(you)，几毫欧的(de)(de)(de)也有。

MOS在(zai)导(dao)通和(he)截止的(de)时(shi)候，一(yi)定不(bu)是(shi)(shi)在(zai)瞬间(jian)完(wan)成的(de)。MOS两端的(de)电压(ya)有(you)一(yi)个下降的(de)过程，流过的(de)电流有(you)一(yi)个上升(sheng)的(de)过程，在(zai)这段时(shi)间(jian)内，MOS管的(de)损(sun)(sun)(sun)(sun)失(shi)是(shi)(shi)电压(ya)和(he)电流的(de)乘积，叫(jiao)做(zuo)开关损(sun)(sun)(sun)(sun)失(shi)。通常开关损(sun)(sun)(sun)(sun)失(shi)比导(dao)通损(sun)(sun)(sun)(sun)失(shi)大得多，而(er)且开关频率越快，损(sun)(sun)(sun)(sun)失(shi)也越大。

导通瞬(shun)间电压和电流的(de)(de)乘积很大(da)，造(zao)成的(de)(de)损失也就很大(da)。缩(suo)短开关(guan)时(shi)间，可以(yi)(yi)(yi)减小(xiao)每次导通时(shi)的(de)(de)损失;降低(di)开关(guan)频(pin)率，可以(yi)(yi)(yi)减小(xiao)单位时(shi)间内(nei)的(de)(de)开关(guan)次数(shu)。这两种办(ban)法(fa)都可以(yi)(yi)(yi)减小(xiao)开关(guan)损失。

第二种：mos管开关电路图

图中电(dian)(dian)(dian)(dian)(dian)(dian)(dian)池的(de)(de)(de)(de)(de)(de)正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)通(tong)(tong)(tong)过(guo)(guo)开关S1接(jie)(jie)(jie)到(dao)(dao)场效应管(guan)(guan)Q1的(de)(de)(de)(de)(de)(de)2脚(jiao)(jiao)(jiao)(jiao)源极(ji)(ji)(ji)，由于(yu)Q1是一(yi)个(ge)(ge)P沟(gou)道管(guan)(guan)，它的(de)(de)(de)(de)(de)(de)1脚(jiao)(jiao)(jiao)(jiao)栅(zha)极(ji)(ji)(ji)通(tong)(tong)(tong)过(guo)(guo)R20电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)提供一(yi)个(ge)(ge)正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)，所以不(bu)(bu)(bu)(bu)能通(tong)(tong)(tong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)能继(ji)续通(tong)(tong)(tong)过(guo)(guo)，3v稳(wen)(wen)压(ya)(ya)(ya)(ya)IC输(shu)入脚(jiao)(jiao)(jiao)(jiao)得不(bu)(bu)(bu)(bu)到(dao)(dao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)所以就(jiu)不(bu)(bu)(bu)(bu)能工(gong)(gong)作(zuo)不(bu)(bu)(bu)(bu)开机(ji)！这(zhei)时，如果(guo)我(wo)们(men)按下SW1开机(ji)按键时，正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)通(tong)(tong)(tong)过(guo)(guo)按键、R11、R23、D4加到(dao)(dao)三(san)极(ji)(ji)(ji)管(guan)(guan)Q2的(de)(de)(de)(de)(de)(de)基(ji)(ji)极(ji)(ji)(ji)，三(san)极(ji)(ji)(ji)管(guan)(guan)Q2的(de)(de)(de)(de)(de)(de)基(ji)(ji)极(ji)(ji)(ji)得到(dao)(dao)一(yi)个(ge)(ge)正(zheng)(zheng)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位，三(san)极(ji)(ji)(ji)管(guan)(guan)导(dao)(dao)通(tong)(tong)(tong)（前面(mian)讲(jiang)到(dao)(dao)三(san)极(ji)(ji)(ji)管(guan)(guan)的(de)(de)(de)(de)(de)(de)时候已经讲(jiang)过(guo)(guo)），由于(yu)三(san)极(ji)(ji)(ji)管(guan)(guan)的(de)(de)(de)(de)(de)(de)发射(she)极(ji)(ji)(ji)直接(jie)(jie)(jie)接(jie)(jie)(jie)地，三(san)极(ji)(ji)(ji)管(guan)(guan)Q2导(dao)(dao)通(tong)(tong)(tong)就(jiu)相当于(yu)Q1的(de)(de)(de)(de)(de)(de)栅(zha)极(ji)(ji)(ji)直接(jie)(jie)(jie)接(jie)(jie)(jie)地，加在它上(shang)面(mian)的(de)(de)(de)(de)(de)(de)通(tong)(tong)(tong)过(guo)(guo)R20电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)的(de)(de)(de)(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)就(jiu)直接(jie)(jie)(jie)入了地，Q1的(de)(de)(de)(de)(de)(de)栅(zha)极(ji)(ji)(ji)就(jiu)从(cong)高电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位变为低电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位，Q1导(dao)(dao)通(tong)(tong)(tong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)就(jiu)从(cong)Q1同(tong)过(guo)(guo)加到(dao)(dao)3v稳(wen)(wen)压(ya)(ya)(ya)(ya)IC的(de)(de)(de)(de)(de)(de)输(shu)入脚(jiao)(jiao)(jiao)(jiao)，3v稳(wen)(wen)压(ya)(ya)(ya)(ya)IC就(jiu)是那个(ge)(ge)U1输(shu)出(chu)3v的(de)(de)(de)(de)(de)(de)工(gong)(gong)作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)vcc供给主(zhu)控(kong)(kong)(kong)，主(zhu)控(kong)(kong)(kong)通(tong)(tong)(tong)过(guo)(guo)复位清(qing)0，读取固件(jian)(jian)程序检(jian)测等(deng)一(yi)系列(lie)动(dong)作(zuo)，输(shu)处一(yi)个(ge)(ge)控(kong)(kong)(kong)制(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)到(dao)(dao)PWR_ON再通(tong)(tong)(tong)过(guo)(guo)R24、R13分(fen)压(ya)(ya)(ya)(ya)送(song)到(dao)(dao)Q2的(de)(de)(de)(de)(de)(de)基(ji)(ji)极(ji)(ji)(ji)，保持Q2一(yi)直处于(yu)导(dao)(dao)通(tong)(tong)(tong)状态(tai)，即使你松开开机(ji)键断开Q1的(de)(de)(de)(de)(de)(de)基(ji)(ji)极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)，这(zhei)时候有主(zhu)控(kong)(kong)(kong)送(song)来的(de)(de)(de)(de)(de)(de)控(kong)(kong)(kong)制(zhi)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)保持着，Q2也就(jiu)一(yi)直能够处于(yu)导(dao)(dao)通(tong)(tong)(tong)状态(tai)，Q1就(jiu)能源源不(bu)(bu)(bu)(bu)断的(de)(de)(de)(de)(de)(de)给3v稳(wen)(wen)压(ya)(ya)(ya)(ya)IC提供工(gong)(gong)作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)！SW1还同(tong)时通(tong)(tong)(tong)过(guo)(guo)R11、R30两个(ge)(ge)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)的(de)(de)(de)(de)(de)(de)分(fen)压(ya)(ya)(ya)(ya)，给主(zhu)控(kong)(kong)(kong)PLAYON脚(jiao)(jiao)(jiao)(jiao)送(song)去时间长短、次数不(bu)(bu)(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)控(kong)(kong)(kong)制(zhi)信(xin)号，主(zhu)控(kong)(kong)(kong)通(tong)(tong)(tong)过(guo)(guo)固件(jian)(jian)鉴别(bie)是播放、暂停、开机(ji)、关机(ji)而输(shu)出(chu)不(bu)(bu)(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)结果(guo)给相应的(de)(de)(de)(de)(de)(de)控(kong)(kong)(kong)制(zhi)点，以达到(dao)(dao)不(bu)(bu)(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)工(gong)(gong)作(zuo)状态(tai)！

第三种：mos管开关电路图

下图是两种MOS管(guan)的(de)典型应用：其中第(di)(di)一种NMOS管(guan)为(wei)(wei)高电(dian)平(ping)导(dao)通(tong)，低电(dian)平(ping)截断，Drain端接后面电(dian)路(lu)的(de)接地端；第(di)(di)二种为(wei)(wei)PMOS管(guan)典型开(kai)关电(dian)路(lu)，为(wei)(wei)高电(dian)平(ping)断开(kai)，低电(dian)平(ping)导(dao)通(tong)，Drain端接后面电(dian)路(lu)的(de)VCC端。

第四种：mos管开关电路图

驱动电路加速MOS管关断时间

图(tu)5 隔离驱动

为(wei)了满(man)足(zu)(zu)如图(tu)5所示高端(duan)MOS管的(de)驱动(dong)，经常会采用变压器(qi)驱动(dong)，有时为(wei)了满(man)足(zu)(zu)安(an)全隔离也使用变压器(qi)驱动(dong)。其(qi)中R1目(mu)的(de)是抑制PCB板上寄生的(de)电感(gan)与C1形成LC振荡，C1的(de)目(mu)的(de)是隔开直流，通过交流，同(tong)时也能防止磁芯饱(bao)和。

第五种：mos管开关电路图

图7（a）为常用(yong)的(de)小(xiao)功率驱动电路(lu)，简单可靠成(cheng)本低。适用(yong)于(yu)(yu)不要求隔离(li)的(de)小(xiao)功率开(kai)关设(she)备(bei)。图7（b）所示驱动电路(lu)开(kai)关速度很快，驱动能力强，为防止两(liang)个MOSFET管直通，通常串接一个0.5～1Ω小(xiao)电阻用(yong)于(yu)(yu)限流，该电路(lu)适用(yong)于(yu)(yu)不要求隔离(li)的(de)中功率开(kai)关设(she)备(bei)。这两(liang)种(zhong)电路(lu)特点是结构简单。

功率(lv)MOSFET属于(yu)电(dian)(dian)(dian)压(ya)型控制器件，只要栅极和源(yuan)极之间施加的电(dian)(dian)(dian)压(ya)超过(guo)(guo)其(qi)阀值电(dian)(dian)(dian)压(ya)就(jiu)会导通。由于(yu)MOSFET存在(zai)结(jie)电(dian)(dian)(dian)容，关断时其(qi)漏源(yuan)两(liang)端电(dian)(dian)(dian)压(ya)的突然上升将会通过(guo)(guo)结(jie)电(dian)(dian)(dian)容在(zai)栅源(yuan)两(liang)端产生干(gan)(gan)(gan)扰电(dian)(dian)(dian)压(ya)。常用的互补(bu)驱动电(dian)(dian)(dian)路的关断回路阻抗(kang)小，关断速度较快，但它不能提供(gong)负压(ya)，故(gu)抗(kang)干(gan)(gan)(gan)扰性较差。为了提高电(dian)(dian)(dian)路的抗(kang)干(gan)(gan)(gan)扰性，可在(zai)此种(zhong)驱动电(dian)(dian)(dian)路的基础上增(zeng)加一级(ji)有V1、V2、R组成的电(dian)(dian)(dian)路，产生一个负压(ya)，电(dian)(dian)(dian)路原(yuan)理图(tu)如图(tu)8所示。

当(dang)V1导通(tong)时，V2关(guan)断，两(liang)个MOSFET中的(de)上(shang)(shang)管(guan)(guan)(guan)的(de)栅(zha)、源极(ji)(ji)(ji)放(fang)电(dian)，下(xia)管(guan)(guan)(guan)的(de)栅(zha)、源极(ji)(ji)(ji)充电(dian)，即上(shang)(shang)管(guan)(guan)(guan)关(guan)断，下(xia)管(guan)(guan)(guan)导通(tong)，则被(bei)驱(qu)动(dong)的(de)功率(lv)管(guan)(guan)(guan)关(guan)断;反之(zhi)V1关(guan)断时，V2导通(tong)，上(shang)(shang)管(guan)(guan)(guan)导通(tong)，下(xia)管(guan)(guan)(guan)关(guan)断，使驱(qu)动(dong)的(de)管(guan)(guan)(guan)子导通(tong)。因为(wei)上(shang)(shang)下(xia)两(liang)个管(guan)(guan)(guan)子的(de)栅(zha)、源极(ji)(ji)(ji)通(tong)过(guo)不(bu)(bu)同的(de)回路充放(fang)电(dian)，包含有V2的(de)回路，由(you)于V2会不(bu)(bu)断退出饱和(he)直至关(guan)断，所(suo)以(yi)对于S1而(er)言导通(tong)比关(guan)断要慢，对于S2而(er)言导通(tong)比关(guan)断要快，所(suo)以(yi)两(liang)管(guan)(guan)(guan)发(fa)热程度也不(bu)(bu)完(wan)全一样(yang)，S1比S2发(fa)热严重。

该驱动电路的缺点是需(xu)要双电源，且由于R的取值不能过(guo)大，否则(ze)会使V1深度(du)饱和，影响关断速(su)度(du)，所(suo)以R上会有一定的损耗(hao)。

第六种：mos管开关电路图

正激式驱动电路

电(dian)路(lu)原理如图9（a）所示，N3为(wei)去磁(ci)绕组，S2为(wei)所驱动的功(gong)率(lv)管。R2为(wei)防(fang)止功(gong)率(lv)管栅(zha)极、源极端电(dian)压(ya)振荡(dang)的一个阻(zu)尼电(dian)阻(zu)。因不要求漏感较小，且从速(su)度(du)方面考虑，一般R2较小，故在分析(xi)中(zhong)忽略不计。

其等效电(dian)(dian)(dian)路图如(ru)图9（b）所示脉(mai)冲不要求(qiu)的(de)(de)(de)(de)副边并联(lian)一(yi)电(dian)(dian)(dian)阻R1，它(ta)做为正激变(bian)换器的(de)(de)(de)(de)假负载(zai)，用于消除关断期间输(shu)出电(dian)(dian)(dian)压发生振(zhen)荡(dang)而误导(dao)(dao)通。同时(shi)它(ta)还可(ke)(ke)以(yi)作(zuo)为功率MOSFET关断时(shi)的(de)(de)(de)(de)能量泄放回(hui)路。该驱(qu)动(dong)电(dian)(dian)(dian)路的(de)(de)(de)(de)导(dao)(dao)通速(su)(su)度主要与被驱(qu)动(dong)的(de)(de)(de)(de)S2栅(zha)极(ji)、源极(ji)等效输(shu)入(ru)电(dian)(dian)(dian)容(rong)的(de)(de)(de)(de)大(da)(da)小(xiao)(xiao)、S1的(de)(de)(de)(de)驱(qu)动(dong)信号的(de)(de)(de)(de)速(su)(su)度以(yi)及(ji)S1所能提供(gong)的(de)(de)(de)(de)电(dian)(dian)(dian)流大(da)(da)小(xiao)(xiao)有(you)关。由仿(fang)真(zhen)及(ji)分析可(ke)(ke)知，占空比(bi)D越(yue)小(xiao)(xiao)、R1越(yue)大(da)(da)、L越(yue)大(da)(da)，磁化电(dian)(dian)(dian)流越(yue)小(xiao)(xiao)，U1值(zhi)越(yue)小(xiao)(xiao)，关断速(su)(su)度越(yue)慢。该电(dian)(dian)(dian)路具(ju)有(you)以(yi)下优点：①电(dian)(dian)(dian)路结(jie)构简单(dan)可(ke)(ke)靠(kao)，实现了(le)隔离驱(qu)动(dong)。②只需单(dan)电(dian)(dian)(dian)源即可(ke)(ke)提供(gong)导(dao)(dao)通时(shi)的(de)(de)(de)(de)正、关断时(shi)负压。③占空比(bi)固定时(shi)，通过合理的(de)(de)(de)(de)参数(shu)设计，此驱(qu)动(dong)电(dian)(dian)(dian)路也具(ju)有(you)较快的(de)(de)(de)(de)开关速(su)(su)度。

该电路存在(zai)的缺点(dian)：一是由于(yu)隔离变压器副边(bian)需要噎嗝假负(fu)载防振荡(dang)，故电路损(sun)耗(hao)较大(da);二是当占空比(bi)变化时关断(duan)速(su)(su)度变化较大(da)。脉宽较窄时，由于(yu)是储存的能(neng)量减少导致MOSFET栅极的关断(duan)速(su)(su)度变慢。

第七种：mos管开关电路图

有隔离变压器的互补驱动电路

如图10所示，V1、V2为(wei)互补工作，电容C起隔离(li)直(zhi)流(liu)的(de)作用，T1为(wei)高频、高磁(ci)率的(de)磁(ci)环(huan)或磁(ci)罐。

导通时(shi)隔(ge)离变(bian)压(ya)器上的电(dian)压(ya)为（1-D）Ui、关断时(shi)为DUi，若主功(gong)率管S可(ke)靠导通电(dian)压(ya)为12V，而隔(ge)离变(bian)压(ya)器原副边匝比N1/N2为12/［（1-D）Ui］。为保证导通期间GS电(dian)压(ya)稳定C值可(ke)稍取大些。该电(dian)路具有以下优(you)点：

①电路结构简(jian)单可靠，具有电气隔离作(zuo)用。当(dang)脉宽(kuan)变化(hua)时，驱动(dong)的关断能力不会(hui)随着变化(hua)。

②该电路(lu)只需一(yi)(yi)个电源(yuan)，即为单电源(yuan)工作。隔直电容C的作用可(ke)以在(zai)关断(duan)所驱(qu)动的管子时提供一(yi)(yi)个负压，从而加速了功率管的关断(duan)，且有较高(gao)的抗干扰(rao)能力。

但该(gai)电(dian)(dian)(dian)(dian)(dian)路存在(zai)的(de)一个(ge)较(jiao)大缺(que)点是输出电(dian)(dian)(dian)(dian)(dian)压(ya)的(de)幅值(zhi)会随着占空(kong)比(bi)(bi)的(de)变化而变化。当D较(jiao)小时(shi)(shi)(shi)，负向电(dian)(dian)(dian)(dian)(dian)压(ya)小，该(gai)电(dian)(dian)(dian)(dian)(dian)路的(de)抗干扰性变差(cha)，且正向电(dian)(dian)(dian)(dian)(dian)压(ya)较(jiao)高，应(ying)该(gai)注意(yi)使(shi)其幅值(zhi)不(bu)超过MOSFET栅极(ji)的(de)允许电(dian)(dian)(dian)(dian)(dian)压(ya)。当D大于(yu)(yu)0.5时(shi)(shi)(shi)驱动电(dian)(dian)(dian)(dian)(dian)压(ya)正向电(dian)(dian)(dian)(dian)(dian)压(ya)小于(yu)(yu)其负向电(dian)(dian)(dian)(dian)(dian)压(ya)，此时(shi)(shi)(shi)应(ying)该(gai)注意(yi)使(shi)其负电(dian)(dian)(dian)(dian)(dian)压(ya)值(zhi)不(bu)超过MOAFET栅极(ji)允许电(dian)(dian)(dian)(dian)(dian)压(ya)。所以该(gai)电(dian)(dian)(dian)(dian)(dian)路比(bi)(bi)较(jiao)适用于(yu)(yu)占空(kong)比(bi)(bi)固定或占空(kong)比(bi)(bi)变化范围(wei)不(bu)大以及占空(kong)比(bi)(bi)小于(yu)(yu)0.5的(de)场合。

第八种：mos管开关电路图

集成芯片UC3724/3725构成的驱动电路

电(dian)(dian)(dian)路构成如图11所示(shi)。其中UC3724用来产(chan)生高(gao)(gao)频(pin)(pin)载(zai)波信号(hao)(hao)，载(zai)波频(pin)(pin)率(lv)由电(dian)(dian)(dian)容CT和电(dian)(dian)(dian)阻RT决定。一(yi)般(ban)(ban)载(zai)波频(pin)(pin)率(lv)小(xiao)(xiao)于600kHz，4脚(jiao)(jiao)和6脚(jiao)(jiao)两端产(chan)生高(gao)(gao)频(pin)(pin)调制波，经高(gao)(gao)频(pin)(pin)小(xiao)(xiao)磁环变(bian)压器(qi)隔离后(hou)送到(dao)UC3725芯(xin)片7、8两脚(jiao)(jiao)经UC3725进行(xing)调制后(hou)得到(dao)驱动(dong)信号(hao)(hao)，UC3725内(nei)部有一(yi)肖特基整(zheng)流(liu)桥同(tong)时(shi)将7、8脚(jiao)(jiao)的高(gao)(gao)频(pin)(pin)调制波整(zheng)流(liu)成一(yi)直流(liu)电(dian)(dian)(dian)压供(gong)驱动(dong)所需功(gong)率(lv)。一(yi)般(ban)(ban)来说载(zai)波频(pin)(pin)率(lv)越(yue)高(gao)(gao)驱动(dong)延时(shi)越(yue)小(xiao)(xiao)，但(dan)太高(gao)(gao)抗干扰变(bian)差;隔离变(bian)压器(qi)磁化电(dian)(dian)(dian)感越(yue)大磁化电(dian)(dian)(dian)流(liu)越(yue)小(xiao)(xiao)，UC3724发热越(yue)少(shao)，但(dan)太大使(shi)匝数(shu)增多(duo)导致寄生参数(shu)影(ying)响变(bian)大，同(tong)样(yang)会使(shi)抗干扰能力降(jiang)低(di)。

根(gen)据实验数据得出：

对于(yu)(yu)开关频(pin)率(lv)(lv)小(xiao)于(yu)(yu)100kHz的(de)信(xin)号(hao)(hao)一般取（400～500）kHz载波(bo)频(pin)率(lv)(lv)较(jiao)好(hao)，变压器选用(yong)较(jiao)高磁导如5K、7K等高频(pin)环(huan)形磁芯，其原边(bian)磁化(hua)电(dian)(dian)(dian)感小(xiao)于(yu)(yu)约1毫亨左右为好(hao)。这种驱动(dong)电(dian)(dian)(dian)路仅(jin)(jin)适合于(yu)(yu)信(xin)号(hao)(hao)频(pin)率(lv)(lv)小(xiao)于(yu)(yu)100kHz的(de)场(chang)合，因信(xin)号(hao)(hao)频(pin)率(lv)(lv)相(xiang)对载波(bo)频(pin)率(lv)(lv)太(tai)高的(de)话，相(xiang)对延时太(tai)多，且(qie)所(suo)需驱动(dong)功率(lv)(lv)增(zeng)大，UC3724和UC3725芯片发热温(wen)升较(jiao)高，故100kHz以(yi)上开关频(pin)率(lv)(lv)仅(jin)(jin)对较(jiao)小(xiao)极电(dian)(dian)(dian)容(rong)的(de)MOSFET才(cai)可以(yi)。对于(yu)(yu)1kVA左右开关频(pin)率(lv)(lv)小(xiao)于(yu)(yu)100kHz的(de)场(chang)合，它是(shi)一种良(liang)好(hao)的(de)驱动(dong)电(dian)(dian)(dian)路。该电(dian)(dian)(dian)路具(ju)有以(yi)下特(te)点：单电(dian)(dian)(dian)源工作，控制(zhi)信(xin)号(hao)(hao)与驱动(dong)实现隔(ge)离，结构简(jian)单尺寸较(jiao)小(xiao)，尤其适用(yong)于(yu)(yu)占空比变化(hua)不确定或信(xin)号(hao)(hao)频(pin)率(lv)(lv)也(ye)变化(hua)的(de)场(chang)合。

第九种：mos管开关电路图

第一(yi)种应用(yong)，由(you)PMOS来(lai)进行电压(ya)(ya)的(de)(de)选择(ze)，当V8V存在时(shi)，此时(shi)电压(ya)(ya)全部由(you)V8V提供，将PMOS关闭，VBAT不(bu)提供电压(ya)(ya)给VSIN，而当V8V为低时(shi)，VSIN由(you)8V供电。注意(yi)R120的(de)(de)接地(di)，该(gai)电阻能(neng)将栅极电压(ya)(ya)稳定地(di)拉低，确保(bao)PMOS的(de)(de)正常开(kai)启，这(zhei)也是(shi)前文所描述(shu)的(de)(de)栅极高阻抗所带(dai)来(lai)的(de)(de)状态隐患。D9和D10的(de)(de)作用(yong)在于防止电压(ya)(ya)的(de)(de)倒灌(guan)。D9可以省略。这(zhei)里要(yao)(yao)注意(yi)到实(shi)际上该(gai)电路的(de)(de)DS接反(fan)，这(zhei)样由(you)附生二极管导通导致了开(kai)关管的(de)(de)功(gong)能(neng)不(bu)能(neng)达到，实(shi)际应用(yong)要(yao)(yao)注意(yi)。

来看(kan)这个电(dian)路，控(kong)制信(xin)号PGC控(kong)制V4.2是否给(ji)(ji)P_GPRS供电(dian)。此(ci)电(dian)路中，源漏两端(duan)没有(you)接反，R110与R113存在的意(yi)义在于R110控(kong)制栅极电(dian)流不至于过大，R113控(kong)制栅极的常(chang)态，将(jiang)R113上(shang)(shang)拉(la)(la)为高，截至PMOS，同时(shi)也可(ke)以(yi)看(kan)作是对(dui)控(kong)制信(xin)号的上(shang)(shang)拉(la)(la)，当MCU内部(bu)管脚并(bing)没有(you)上(shang)(shang)拉(la)(la)时(shi)，即(ji)输出为开漏时(shi)，并(bing)不能驱动PMOS关闭(bi)，此(ci)时(shi)，就需要外部(bu)电(dian)压给(ji)(ji)予的上(shang)(shang)拉(la)(la)，所以(yi)电(dian)阻R113起到(dao)了两个作用。R110可(ke)以(yi)更小，到(dao)100欧姆也可(ke)。

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