MOS管(guan)的作(zuo)用(yong)

MOS管(guan)(guan)(guan)(guan)为压控(kong)元(yuan)件,你只需加到它(ta)的压控(kong)元(yuan)件所需电(dian)(dian)压就(jiu)能使它(ta)导通(tong)(tong),它(ta)的导通(tong)(tong)就(jiu)像(xiang)三极管(guan)(guan)(guan)(guan)在饱(bao)和状态(tai)一样,导通(tong)(tong)结的压降最小.这(zhei)就(jiu)是常(chang)(chang)说(shuo)的精(jing)典是开(kai)关(guan)(guan)作用(yong).去掉这(zhei)个(ge)控(kong)制(zhi)电(dian)(dian)压经(jing)就(jiu)截止. MOS管(guan)(guan)(guan)(guan)的英文全称叫MOSFET，即金属(shu)(shu)氧化物半导体型场效应管(guan)(guan)(guan)(guan)，属(shu)(shu)于场效应晶体管(guan)(guan)(guan)(guan)中(zhong)的绝缘栅型。因而(er)，MOS管(guan)(guan)(guan)(guan)有时被称为场效应管(guan)(guan)(guan)(guan)。在普通(tong)(tong)电(dian)(dian)子电(dian)(dian)路中(zhong)，MOS管(guan)(guan)(guan)(guan)通(tong)(tong)常(chang)(chang)被用(yong)于放大电(dian)(dian)路或开(kai)关(guan)(guan)电(dian)(dian)路。而(er)在主板(ban)(ban)上(shang)的电(dian)(dian)源(yuan)稳压电(dian)(dian)路中(zhong)，MOSFET扮演(yan)的角色主要是判别电(dian)(dian)位，它(ta)在主板(ban)(ban)上(shang)常(chang)(chang)用(yong)“Q”加数字(zi)表示。

一(yi)、MOS管作(zuo)用是(shi)什么？

MOS管，即(ji)在(zai)集(ji)成电路中绝缘(yuan)性(xing)场效(xiao)应管。MOS英文全称(cheng)为(wei)金属-氧化物-半导(dao)体，描述了集(ji)成电路中的结构(gou)，即(ji)：在(zai)一定结构(gou)的半导(dao)体器件上，加(jia)上二氧化硅和金属，形(xing)成栅极。MOS管的source和drain是可以对(dui)调(diao)的，都是在(zai)P型backgate中形(xing)成的N型区。

MOS管(guan)可(ke)(ke)(ke)以(yi)用(yong)(yong)(yong)(yong)作可(ke)(ke)(ke)变(bian)电(dian)(dian)(dian)阻(zu)也(ye)可(ke)(ke)(ke)应(ying)用(yong)(yong)(yong)(yong)于(yu)放(fang)大(da)(da)。由于(yu)场效(xiao)(xiao)应(ying)管(guan)放(fang)大(da)(da)器(qi)(qi)的输入(ru)阻(zu)抗很(hen)高(gao)，因此耦合电(dian)(dian)(dian)容可(ke)(ke)(ke)以(yi)容量较(jiao)小(xiao)，不必(bi)使用(yong)(yong)(yong)(yong)电(dian)(dian)(dian)解电(dian)(dian)(dian)容器(qi)(qi)。且(qie)场效(xiao)(xiao)应(ying)管(guan)很(hen)高(gao)的输入(ru)阻(zu)抗非(fei)常(chang)适(shi)合作阻(zu)抗变(bian)换。常(chang)用(yong)(yong)(yong)(yong)于(yu)多(duo)级放(fang)大(da)(da)器(qi)(qi)的输入(ru)级作阻(zu)抗变(bian)换。场效(xiao)(xiao)应(ying)管(guan)可(ke)(ke)(ke)以(yi)方便地用(yong)(yong)(yong)(yong)作恒流源也(ye)可(ke)(ke)(ke)以(yi)用(yong)(yong)(yong)(yong)作电(dian)(dian)(dian)子开关(guan)。

有些场效应管的源极和漏(lou)极可以互换使(shi)用，栅压(ya)也可正可负，灵(ling)活性比(bi)晶体(ti)管好。场效应(ying)管能在很小(xiao)电(dian)流和很低(di)电(dian)压的条件下工(gong)作，而(er)且它(ta)的制造(zao)工(gong)艺(yi)可以很方便地把很多场(chang)效应管(guan)集成在一块硅片(pian)上，因此场(chang)效应管(guan)在大规模集成电(dian)路(lu)中得到(dao)了广泛的应用(yong)。

在(zai)一般电(dian)子电(dian)路中(zhong)(zhong)，通常(chang)被用于放大(da)电(dian)路或开关(guan)电(dian)路。而在(zai)主板上(shang)的电(dian)源稳(wen)压电(dian)路中(zhong)(zhong)，MOSFET扮演的角(jiao)色主(zhu)(zhu)要是判断电位(wei)，它(ta)在主(zhu)(zhu)板(ban)上(shang)常用“Q”加数字表示(shi)。

目前在(zai)主板或(huo)显卡上(shang)所采用的(de)并不是(shi)(shi)太多，一(yi)(yi)般(ban)(ban)有(you)10个左右，主要原因是(shi)(shi)大部分被整合到IC芯(xin)片中(zhong)去了(le)。由于主要是(shi)(shi)为配件(jian)提供稳(wen)定(ding)的(de)电(dian)压，所以它一(yi)(yi)般(ban)(ban)使用在(zai)CPU、AGP插(cha)(cha)槽(cao)和内存插(cha)(cha)槽(cao)附近。其中(zhong)在(zai)CPU与AGP插(cha)(cha)槽(cao)附近各安(an)排一(yi)(yi)组(zu)(zu)MOS管(guan)，而内存插(cha)(cha)槽(cao)则共(gong)用了(le)一(yi)(yi)组(zu)(zu)MOS管(guan)，一(yi)(yi)般(ban)(ban)是(shi)(shi)以两个组(zu)(zu)成一(yi)(yi)组(zu)(zu)的(de)形式出(chu)现主板上(shang)的(de)。

还有一个(ge)非(fei)常重要的性能参数。主要包括环境(jing)温(wen)度、管(guan)(guan)壳温(wen)度、贮成温(wen)度等。由于CPU频(pin)率(lv)的提高，MOS管(guan)(guan)需要承受的电流(liu)也随着增强，提供近百A的电流(liu)已经很常见(jian)了。

二(er)、MOS管(guan)的性能参数有哪些(xie)？

优质的(de)MOS管(guan)(guan)可以接(jie)受(shou)(shou)的(de)电流(liu)峰值更高。普通状况下我们(men)要(yao)判别主(zhu)(zhu)板上MOS管(guan)(guan)的(de)质量(liang)(liang)上下，能够(gou)(gou)看它能接(jie)受(shou)(shou)的(de)最大电流(liu)值。影响MOS管(guan)(guan)质量(liang)(liang)上下的(de)参数(shu)十(shi)分多，像(xiang)极(ji)端(duan)电流(liu)、极(ji)端(duan)电压等。但在(zai)MOS管(guan)(guan)上无法(fa)标(biao)注这么(me)多参数(shu)，所以在(zai)MOS管(guan)(guan)外表普通只标(biao)注了(le)产品的(de)型号(hao)，我们(men)能够(gou)(gou)依据该型号(hao)上网查(cha)找详细的(de)性能参数(shu)。 还要(yao)阐明的(de)是，温度(du)也(ye)是MOS管(guan)(guan)一(yi)个十(shi)分重要(yao)的(de)性能参数(shu)。主(zhu)(zhu)要(yao)包括环境温度(du)、管(guan)(guan)壳温度(du)、贮成温度(du)等。由于CPU频率的(de)进步，MOS管(guan)(guan)需求接(jie)受(shou)(shou)的(de)电流(liu)也(ye)随(sui)着加强，提供近百A的(de)电流(liu)曾经(jing)很常见了(le)。如此宏(hong)大的(de)电流(liu)经(jing)过(guo)时产生的(de)热量(liang)(liang)当(dang)然使MOS管(guan)(guan)“发烧(shao)”了(le)。为了(le)MOS管(guan)(guan)的(de)平安，高质量(liang)(liang)主(zhu)(zhu)板也(ye)开端(duan)为MOS管(guan)(guan)加装散(san)热片了(le)。

三、电感与MOS管是如何协作的？

经(jing)过(guo)上(shang)面的(de)(de)引见，我(wo)们晓得MOS管(guan)(guan)关(guan)(guan)(guan)于(yu)整个供(gong)电(dian)(dian)(dian)(dian)系统(tong)起着(zhe)稳压(ya)(ya)的(de)(de)作(zuo)(zuo)用(yong)，但是MOS管(guan)(guan)不(bu)能(neng)单独运用(yong)，它必需(xu)和电(dian)(dian)(dian)(dian)感线圈、电(dian)(dian)(dian)(dian)容等共同组成的(de)(de)滤波稳压(ya)(ya)电(dian)(dian)(dian)(dian)路，才干发挥充沛它的(de)(de)优势。 主板上(shang)的(de)(de)PWM(PlusWidthModulator，脉冲(chong)宽度(du)调制器(qi))芯片产(chan)生一个宽度(du)可调的(de)(de)脉冲(chong)波形，这(zhei)(zhei)样能(neng)够使两(liang)只MOS管(guan)(guan)轮番导通。当负(fu)载(zai)两(liang)端(duan)(duan)的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)(如CPU需(xu)求的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya))要降(jiang)低时(shi)(shi)，这(zhei)(zhei)时(shi)(shi)MOS管(guan)(guan)的(de)(de)开(kai)(kai)(kai)关(guan)(guan)(guan)作(zuo)(zuo)用(yong)开(kai)(kai)(kai)端(duan)(duan)生效，外部(bu)电(dian)(dian)(dian)(dian)源(yuan)对电(dian)(dian)(dian)(dian)感停止充电(dian)(dian)(dian)(dian)并到达所需(xu)的(de)(de)额定电(dian)(dian)(dian)(dian)压(ya)(ya)。当负(fu)载(zai)两(liang)端(duan)(duan)的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)升高(gao)(gao)时(shi)(shi)，经(jing)过(guo)MOS管(guan)(guan)的(de)(de)开(kai)(kai)(kai)关(guan)(guan)(guan)作(zuo)(zuo)用(yong)，外部(bu)电(dian)(dian)(dian)(dian)源(yuan)供(gong)电(dian)(dian)(dian)(dian)断开(kai)(kai)(kai)，电(dian)(dian)(dian)(dian)感释放出方才充入的(de)(de)能(neng)量，这(zhei)(zhei)时(shi)(shi)的(de)(de)电(dian)(dian)(dian)(dian)感就变成了“电(dian)(dian)(dian)(dian)源(yuan)”，继续(xu)对负(fu)载(zai)供(gong)电(dian)(dian)(dian)(dian)。随着(zhe)电(dian)(dian)(dian)(dian)感上(shang)存(cun)储能(neng)量的(de)(de)不(bu)时(shi)(shi)耗费，负(fu)载(zai)两(liang)端(duan)(duan)的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)又(you)开(kai)(kai)(kai)端(duan)(duan)逐步降(jiang)低，外部(bu)电(dian)(dian)(dian)(dian)源(yuan)经(jing)过(guo)MOS管(guan)(guan)的(de)(de)开(kai)(kai)(kai)关(guan)(guan)(guan)作(zuo)(zuo)用(yong)又(you)要充电(dian)(dian)(dian)(dian)。这(zhei)(zhei)样循环不(bu)时(shi)(shi)地停止充电(dian)(dian)(dian)(dian)和放电(dian)(dian)(dian)(dian)的(de)(de)过(guo)程，从而构成一种稳定的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)，永远使负(fu)载(zai)两(liang)端(duan)(duan)的(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)不(bu)会升高(gao)(gao)也不(bu)会降(jiang)低。

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