【正文】 (圖一) (圖二) 從(圖二)穩(wěn)壓特性曲線可以看出,當(dāng)穩(wěn)壓管反向擊穿后,流過(guò)二極管的工作電流發(fā)生很大變化時(shí),穩(wěn)壓二極管的電壓降壓V2基本不變,那么穩(wěn)壓管處于截止?fàn)顟B(tài),即開(kāi)路.3. 主要參數(shù)(1) 穩(wěn)定電壓(2) 穩(wěn)定電流:穩(wěn)壓管工作對(duì)參考電流值,電流小于該值,穩(wěn)壓效果會(huì)略差 些.(3) 額定功率損耗(4) 電壓溫度系數(shù)(5) 動(dòng)態(tài)電阻(又稱晶體三極管) TRANSISTORTest Description1hFEForwardcurrent transfer ratio2VBEBase emitter voltage(see also Appendix F)3IEBOEmitter to base cutoff current 4VCESATSaturation voltage5ICBOCollector to base cutoff current6ICEOCollector to emiter cutoff currentICER,with base to emiter load,ICEX,reverse bias,orICESshort(see also Appendix F)7BVCEOBreakdown voltage,collector to emitter,BVCERwith base to emiter load,BVCEXreverse bias,orBVCESshort(see also Appendix F)8BVCBOBreakdown voltage,collector to base9BVEBOBreakdown voltage,emitter to base10VBESATBase emitter saturation voltage ICc (a)NPN (b)PNPcccccccc 集電極IcbcccIbbcccP=NbcccIbbcccNecccP= N eccccccc Ie (a) NPNecccIe eP= (b) PNP Ie ,構(gòu)成兩個(gè)PN結(jié),即集電結(jié)和發(fā)射結(jié),基結(jié)3個(gè)電極,分別是集電極,基極,發(fā)射極,管子中工作電流有集電極電流Ic,基極電流Ib,發(fā)射極電流Ie,Ie=Ib+Ic Ic=βIb, β為三極管電流放大倍數(shù).ic cE1E1UcUcUbUb E2E2 uceUeUe (1)NPN (2) PNP (3)共發(fā)射極輸出特性曲線(1) 放大區(qū)發(fā)射結(jié)正偏,集電結(jié)反偏,E1E2,即 NPN型三極管VcVbVe,PNP型三極管 VcVb=βIb,即Ic受Ib控制,而Ic的電流能量是由電源提供的,此時(shí)Ube=~(NPN硅管)(2) 截止Ib≦0的區(qū)域稱截止區(qū),UBE,三極開(kāi)始截止,為了截止可靠,常使UBE≦0,即發(fā)射結(jié)零偏或反偏,截止時(shí),集電結(jié)也反向偏置.(3) 飽和區(qū) 當(dāng)VCEVBE,即集電結(jié)正向偏置,發(fā)射結(jié)正向偏置時(shí),三極管處于飽和區(qū).飽和壓降UCE(sat),小功率硅管UCE(sat)≒,鍺管UCE(sat)≒4. 主要參數(shù)(1) 共發(fā)射極直流電流放大系數(shù)β,即Hfe, β=IC/IB(2) 共發(fā)射極交流電流放大系數(shù)β. β=ΔIC/ΔIB(3) 集電極,基極反向飽和電流ICBO(4) 集電極,發(fā)射極反向飽和電流ICEO,即穿透電流(5) 集電極最大允許功耗PCM(6) 集電極最大允許電流ICM(7) 集電極,基極反向擊穿電壓U(BR)CBO(8) 發(fā)射極,基極反向擊穿電壓U(BR)CBO(9) 集電極,發(fā)射極反向擊穿電壓U(BR)CBO(英文簡(jiǎn)稱SCR,也叫晶閘管)SCRTest Description1IGTGatetrigger current2IGKOReverse gate current5VGTGatetrigger voltage6BVGKOReverse gaet breakdown voltage7IDRMForward Blocking current8IRRMReverse Blocking current9ILLatching current11IHHolding current(see also Appendix F)13VTMForward on voltage15VDRMForward blocking voltage16VRRMReverse blocking voltage1. 電路符號(hào) A K 陽(yáng)極 G 控制極 陰極2. 工作原理(1) 在陽(yáng),陰極間加上一個(gè)正電壓,再在控制極和陰極之間加上正電壓,可控硅導(dǎo)通.(2) 可控硅導(dǎo)通后,去掉控制極上