AN920 D PDF

Publication Order Number: AN/D. AN/D GENERAL DESCRIPTION The MC series is a monolithic control circuit containing all the active functions. And Mc Pwm Controler – Download as PDF File .pdf), Text File .txt) or read online. AN/D for additional design information. The excel spread sheet for thermal considerations is available too. The MC is an extended temperature.

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DC-DC Step-Up Converter

Thisis becausethethresholdvoltageofthecurrentlimitsense circuitexhibitsasoftvoltageturn-oncharacteristicand hasaturn-offtimedelaythatcausessomeovershoot. A78S40 are monolithic switching regulator subsystems intended aan920 use as dc to dc con- verters. This signal is used to vary the resistance of the series-pass element in a corrective fashion in order to maintain a constant output voltage under varying input voltage and output load conditions. AvalueforthecurrentlimitresistorRsccanbedeter- minedbyusingthecurrentlevelofIpk switch whenVin.

Thesubstratecurrentwillbeabout 10percentofthecatchdiodecurrentinthestep-upcon- fvioglutraagtieo-innvaenrtdinagbinouwth2i0chppeirnce1n1tiisnctohmemstoenp-tdoothwennaengd- ativeoutput. Another major advantage of the switching regulator is that it has increased application flexibility of output volt- age.

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The error amplifier mon- itors the outputvoltage level,compares it to the reference and generates a linearcontrol signal that varies between two extremes, saturation and cutoff. Operationof theswitchingregulator withaseverelyoverloadedorshortedoutputorhaving inanoverloadorshortedconditionwillcauseaveryshort theinputvoltagegrosslyabovethe nominaldesignvalue.

Documents Education Rapports de stage Switched-mode power supply Current.

Article No jsco Available online at http: However,apoint ofdiminishingreturnwillbereachedbecausethecom- paratorrequiresafinitevoltagedifferenceacrossits inputstocontrolthelatch. The output can be less than, greater than, or of opposite polarity to that of the input voltage.

AseparateVCCpinisprovidedinordertoreduce theintegratedcircuitstandbycurrentandisusefulinlow powerapplicationsiftheoperationalamplifierisnot incorporatedintothemainswitchingsystem.

These devices represent a significant advance- ment in the ease of implementing highly efficient and yet simple switching power supplies. Thediodecan be consideredforuseonlyinlowpowerconverterappli- cationswherethetotalsystemcomponentcountmust beheldtoaminimum.

DC-DC Step-Up Converter | Details |

DonotsetRsc toexceedthemaximumlpk switch limitof1. Thistotally eliminatesthediodefrombeingusedinthebasicvoltage invertingconfigurationasinFigure15,sincethesub- strate,pin11,iscommontoground. The use of switching regulators is becoming more pronounced over that of linear regulators because the size reductions In new equipment designs require greater conversion efficiency.

Thusthecom-cycle,multiplecycles,ormultiplecyclesplusaportion paratorcaninitiateoutputswitchconduction,butcannot terminat i e tandthelatchisalwaysresetwhenCTbeginsofCounrerceyntclliem. ThenlL pk attainedduringtonmustdecaytozeroduringtoffanda ratiooftontot0ffcanbewritten. Ichg toffldischgton Figure10showsthestep-upswitchingregulatorwave- forms.

The linear regulator consists of a sta- ble reference, a high gain error amplifier, and a variable resistance series-pass element.

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Order this document by AN D Rev – JADE ALBERKRACK – Rapports de stage

Voir plus Voir moins. Solvingfortiinknown Substitutingfor 1 bk lout 1ok lout termsyields: Inpracticethecurrentlimitcircuitwillsomewhatmod- ifythechargingslopeandpeakamplitudeofCTeach timethe outputswitchisrequiredtoconduct. Thisallowsthedesignetrheoptionofdrivingthe outputswitchtransistorintosaturationwithaselected forcedgainordrivingitnearsaturationwhenconnected asaDarlington.

TheoutputvoltageacrosscapacitorC0willeven- tuallydecaybelownominalbecause itistheonlycom- ponentsupplycurrentintotheexternalloadRL. Thecatch diodeisconstructedfromalateralPNPtransistorandis capableofblockingupto40voltsandwillconductcur- rentsupto1. Thefilteraveragetshesquarewavesproducing adcoutputvoltage thatcanbesettoanylevellessthan theinputbycontrollingthepercentconductiontimeof Qitothatofthetotalswitchingcycletime. Documents Aan920 Rapports de stage. BasicSwitchingRegulatorConfigurations 9N02Theoff-timetoff,isthetimethatdiodeDlisinconduction anditisdeterminedbythetimerequiredfortheinductor currenttoreturntozero.

This butfinitetimeofoutputconductionfollowedbyeithera causesittorapidlyreachtheupperoscillatorthreshold,normalorextendedoff-timeintervalprovidedbythe therebyshorteningthetimeofoutputswitchconductionoscillatorramp-downtimeofCT.

Vin min O,peratio is n attheonset ofcontinuousmodeandtheoutputcurrent capabilitywillbegreaterthan50 mA.

Therequiredvaluefor CTcanbedeterminedbyusingtheminimumoscillator chargingcurrentandthetypicalvaluefortheoscillator voltageswingbothtakenfromthedatasheetelectrical characteristicstable. The voltageacrosstheinductorisequaltoVin Vsat Vout andthepeakcurrentatanyinstantis: Co2tpktoff 1ok lout 2toff 21pkC0.

Referringtothe C02 capacitorcurrentwaveforms inFigure10, t1isdefined asthecapacitorcharginginterval. M4TOROLOABecausetheintegratedcircuitsubstrateiscommon withtheinternalandexternalcircuitryground,thecath- odeofthediodecannotbeoperatedmuchbelowground orforwardbiasingof thesubstratewillresult.

Theoff-timeis notrelated to theramp-downtimeofCT.