第三章元件选择

0.7W1W1W1W0.5W0.7W3.13.1.1PTCNTC3.13.1RT0.1~3W122M±253501350ppm/°CRJ0.1~3W15.1M±0.5525100ppm/°CRY0.25~10W0.1~150k±15100~300ppm/°CRX0.5~10W0.01~10k±11025~100ppm/°C060308051206110M±15100~200ppm/°CRX2~40W0.01~150k±11020~300ppm/°CRX10~1000W0.5~150k±11020~400ppm/°C0.25/4,14102.2M±15100~250ppm/°C0.125~0.250±156,8,101001M±20200ppm/°C1W1kW3.23.2PCB3.1.215.78k87.45101k10k103.351.11.21.31.41.51.6(1.7)1.82.22.42.73.33.63.94.34.75.15.66.26.8(7.5)8.29.15%3.31.21.21212011813.110k110M100M110M100M1M1M1M103.112309451012345100010.1,0.010.001.3.1.3100V500V3.1.41/4W1/2W1/4W70%1W0.5WRN55RN60501/2W1/4W1/4W1/4W0.25W270WW100mW100mW100ms100ms10P=(40V)2/10=160W200WDal3.4E=Pt=160W0.1s16J,E/R=16J/10=1.6J/2.46J/.1010.113.1.51kW300W150W3.1.6193.1.7100A100mV100mV50mV,75mV100mV/100A=1m2.5cm20nHf=1m/220nH8kHzPCBPCBPCBPCB0.4/35m)(5.0Ω=mdlRldPCB70m0.50.253.23.53.5ESRdV/dt3.2.1,(CD)(CA)mFV,100VµF(CC)pF1µFMLCESRµF20CL(CB)(CF)dv/dt(CZ)3.2.21.01.21.5.82.22.73.34.76.85.68.2122pF3.2.410%4080%3.53.7FGCDJKMZ±1±2±0.25pF±0.5pF±5±10±20+80–203.2.5ESR(ESR),120HztanCRESR100kHzESRESR25253ESR1ESR100kHz1A50mV1A(1/100kHz)=10CESRC=Q/U=10C/50mV=200F100F100FESR100m50mVESR50mV/1A50m100FESRESR3100F25ESR300m6650mV17mVUpp=[(502+172)]1/2=53mVESRESRESR(ESR)I2ESRC=50~85106(s)65106(s)ESR3.2.68521MTBFMeanTimebetweenFailures1000200050001101855mm,18353mm6162mmESRESRI2R,3.23.2.73.253.33.3.1Q3/41103.3.212V16A10AMOSFET3.3.3IFtrr=ta+tb(3.3)22trr3.3ta(3.4)tb50V50VMOSFETMOSFET1sMOSFETMOSFETIFtrrtIRtatb3.35~10s3.4GTR)+U-U-U+U3.4GTR(BJTMOSFETIGBT1.2~1.53.4.1BJTICMPCMIs/bU(BR)CEOSOABJTICMPCMU(BR)CEOBJT2BJT()BJT510101BEBEBE5~6V3.5Uce=UDb+UbeUDcUDbUbeUDc0.7VUce=0.7V,Db,1.4VDcIDb3.5U(BR)CEO=450V,50A50kHz233.4.2MOSFETMOS(MetalOxideSemiconductor)MOSFETMOSFETPNPNNNMOSFETNMOSFETMOSFETRon15VP=RonI2T2525007.1)(−×=TRTRMOSFETUgQgP=QgVf0.5MOSFETP=IpkUpktsfs/2UpkMOSFETIpktsfsMOSFETdUg/dtEMIMOSFETMOSFETMOSFETMOSFETMOSFETUT3.6Ugt3.6MOSFETMOSFETMOSFET100MHzEMI20V40V20VMOSFET10ns24MOSFET1MHzkHzMOSFETBJTMOSFETBJT3.63.6UMOSFETBJTTBJTPWMMOSFET(Tr1)MOSFETBJTURBJTBJTBJTTIcD1BJT1/n1/,n=1:10,BJT15BJTBJTMOSFETBJTBEBJTBJTTIcD2RD1UTr2MOSFETTr13.6MOSFETBJTMOSFETBJTU(BR)CER550V,23A60A/50VMOSFET70A/700V(U(BR)CER)BJT50kHzMOSFETIGBTBJTMOSFETMOSFETBJTIGBTMOSFETIGBTBJTIGBTBJTMOSFETBJTIGBT3.4.3IGBTIGBTMOSFETBJTMOSFETBJTBJTPNPNPN500V3.51)2)3)0.2~1s3~5s.4)5)3.63.6.1Uos3.711LM29022mV2mV2mV9.09k+LM290210k100k3.72522mV100mV10011+0.022=1.122V,10.022=1.078V)mV3.6.2LM2902Ib=90nA3.7100k//10k9.1k9.1k19.1k10k9010=900V109mV3.6.3Ios3.7LM29025nA5nA9.1k5nAU=5nA9.1k=45.5V45.5V10,455V,3.6.4GRIRIVVbosos×∆×+×+=)()([GRR3a.Ios±57mAb.Ibc.UosUos3.6.53.81000PCB10M1M10k1k3.93.910mV10mV10mV10k1A90kA90k1A90k90mV1090100mVA100mV1k100A1A98k98k1019.9VA100mV0.1V10V10V/10mV1000100k+VLM2002-V10k10M3.8263.6.73.6.8101V10Vpp200kHz1/40.251/200kHz1.25s10V/1.25s=8V/sµA7411V/µs3.73.7.13.101k/100k0.011%3.7.2LM1396mA0.6V1mANPN0.7VNPNBE3.1110k90k90k1k3.91000VVref1k+100k3.10V++1N4148LM290110k3.11BJT27700mV10k28