直流穩(wěn)壓電源之串聯(lián)型晶體管穩(wěn)壓電路課件講解

直流穩(wěn)壓電源之串聯(lián)型晶體管穩(wěn)壓電路DCRegulatedPowerSupply——TheSeries-connectedTransistorVoltageRegulatorCircuit穩(wěn)壓電路VoltageRegulatorCircuit1、電路結(jié)構(gòu)1并聯(lián)型穩(wěn)壓電路CircuitstructureParallel-connectedvoltageregulatorcircuit學(xué)習(xí)目標(biāo)LearningObjectives了解串聯(lián)反饋式晶體管穩(wěn)壓電路的穩(wěn)壓原理了解穩(wěn)壓電源的主要技術(shù)指標(biāo)Understandthevoltagestabilizationprincipleofseries-connectedfeedbacktransistorvoltageregulatorcircuits.Understandthemaintechnicalspecificationsofvoltageregulatorpowersupplies.串聯(lián)型穩(wěn)壓電源Series-connectedVoltageRegulator1.穩(wěn)壓電源的主要指標(biāo)（1）電壓調(diào)整率SU（2）電流調(diào)整率SI（3）輸出電壓的溫度系數(shù)ST1.KeyParametersofVoltageRegulators(1)VoltageregulationrateSU(2)CurrentregulationrateSI(3)Temperaturecoefficientofoutputvoltage1.電路一般結(jié)構(gòu)

GeneralCircuitStructure串聯(lián)式穩(wěn)壓電路由取樣、基準(zhǔn)電壓、放大和調(diào)整四個(gè)環(huán)節(jié)組成。AUBTUREFUFR1取樣R2UoRL調(diào)整

基準(zhǔn)電壓比較放大∞－＋Ui－＋取樣環(huán)節(jié)：R1R2分壓提取與輸出Uo成正比的取樣電壓UFSamplingStage:ExtractingthesamplingvoltageUFproportionaltotheoutputvoltageUothroughR1

andR2voltagedivision.Theseries-connectedvoltageregulatorcircuitconsistsoffourstages:sampling,referencevoltage,amplification,andadjustmentadjustmentcomparisonandamplificationreferencevoltagesampling串聯(lián)反饋型晶體管穩(wěn)壓電路SeriesFeedbackTransistorVoltageRegulatorCircuit串聯(lián)型穩(wěn)壓電源Series-connectedVoltageRegulator2.穩(wěn)壓原理VoltageStabilizationPrinciple穩(wěn)壓過程按電網(wǎng)波動(dòng)和負(fù)載電阻改變兩種情況分述如下：Thevoltagestabilizationprocessisexplainedseparatelyfortwosituations:fluctuationsinthepowergridandchangesintheloadresistance.當(dāng)電網(wǎng)波動(dòng)Whenthepowergridfluctuates

Ui↑→Uo↑→UF↑→UBE↓→UCE↑→Uo↓；當(dāng)負(fù)載電阻Whentheloadresistancechanges

RL↓→Uo↓→UF↓→UBE↑→UCE↓→Uo↑。電路為電壓串聯(lián)負(fù)反饋，調(diào)整管T連接成射極跟隨器，

因而可得：Thecircuitemploysvoltage-seriesnegativefeedback.TransistorTisconnectedasanemitterfollower.

Therefore,itcanbederived:↑→↑AUBTUREFUFR1取樣R2UoRL調(diào)整

基準(zhǔn)電壓比較放大∞－＋Ui－＋adjustmentcomparisonandamplificationreferencevoltagesampling串聯(lián)型穩(wěn)壓電源Series-connectedVoltageRegulator或or

在深度負(fù)反饋條件下，|1+AuFu|>>1時(shí)，可得當(dāng)反饋越深時(shí)，調(diào)整作用越強(qiáng)，輸出電壓Uo也越穩(wěn)定AUBTUREFUFR1取樣R2UoRL調(diào)整

基準(zhǔn)電壓比較放大∞－＋Ui－＋UCEUBEadjustmentComparisonandamplificationreferencevoltagesamplingUnderconditionsofdeepnegativefeedback,where|1+AuFu|>>1,wecanderive:Asthefeedbackbecomesdeeper,theadjustingeffectbecomesstronger,andtheoutputvoltageUobecomesmorestable.實(shí)際的串聯(lián)式穩(wěn)壓電路ActualSeries-typeVoltageRegulatorCircuit1.穩(wěn)壓過程UoUFUCE2Uo當(dāng)Ui增加或輸出電流減?。≧L增大）使Uo升高時(shí)IB2IC2UBE1UCE1R3T1T2UZRRW1RW2R1RWR2RLUO+_+_UiUFIB2IC2UBE1UCE2UCE1UBE2=（UF－UZ）VoltagestabilizationprocessWhenUiincreasesortheoutputcurrentdecreases(RLincreases),causingUotoriseR3T1T2UZRRW1RW2R1RWR2RLUO+_+_UiUFIB2IC2UBE1UCE2UCE1當(dāng)Ui減小或輸出電流增加（RL減?。┦筓o降低時(shí)UCE2UoIC2UBE1UCE1UoUFIB2UBE2=（UF－UZ）WhenUidecreasesortheoutputcurrentincreases(RLdecreases),causingUotodecreaseR3T1T2UZRRW1RW2R1RWR2RLUO+_+_UiUFIB2IC2UBE1UCE2UCE12.RW的調(diào)壓作用UCE2UoUBE1UCE1RW下調(diào)UFUBE2UZ不變UCE2UoUBE1UCE1RW上調(diào)UFUBE2UZ不變RegulationeffectofofRWRWdecreasedUZunchangedUZunchangedRWincreased實(shí)際的串聯(lián)式穩(wěn)壓電路ActualSeries-typeVoltageRegulatorCircuitR3T1T2UZRRW1RW2R1RWR2RLUO+_+_UiUFIB2IC2UBE1UCE2UCE1KVL:UZ+UBE2=UF分壓公式：Voltagedivisionformula:實(shí)際的串聯(lián)式穩(wěn)壓電路ActualSeries-typeVoltageRegulatorCircuit3.輸出電壓的調(diào)節(jié)范圍Adjustmentrangeoftheoutputvoltage例電路如圖所示。

Example:Giventhecircuitasshowninthediagram.已知UZ=6V，R1=

R2=RP，試估算穩(wěn)壓電路輸出電壓Uo的調(diào)節(jié)范圍。KnownUZ=6V，R1=

R2=RP,trytoestimatetheadjustmentrangeoftheoutputvoltageUoofthevoltageregulatorcircuit.解：由“虛短”，知道UF=UREF=UZ=6V，可估算出：Solution:Duetothe"virtualshort,"weknowU