 |
Zakładka z wyszukiwarką danych komponentów |
|
|
Zakładka z wyszukiwarką danych komponentów |
|
LT3757 Arkusz danych(PDF) 21 Page - Linear Technology |
|
|
|||||||||||||||||||||||||||||
LT3757 Arkusz danych(HTML) 21 Page - Linear Technology |
|
|
21 / 36 page  LT3757 3757fb applicaTions inForMaTion Flyback Converter: Output Diode Selection Theoutputdiodeinaflybackconverterissubjecttolarge RMScurrentandpeakreversevoltagestresses.Afast switchingdiodewithalowforwarddropandalowreverse leakageisdesired.Schottkydiodesarerecommendedif theoutputvoltageisbelow100V. Approximatetherequiredpeakrepetitivereversevoltage ratingVRRMusing: V N N V V RRM S P IN MAX OUT > + • ( ) Thepowerdissipatedbythediodeis: PD=IO(MAX)•VD andthediodejunctiontemperatureis: TJ=TA+PD•RθJA TheRθJAtobeusedinthisequationnormallyincludes theRθJCforthedevice,plusthethermalresistancefrom theboardtotheambienttemperatureintheenclosure.TJ mustnotexceedthediodemaximumjunctiontemperature rating. Flyback Converter: Output Capacitor Selection Theoutputcapacitoroftheflybackconverterhasasimilar operationconditionasthatoftheboostconverter.Referto theBoostConverter:OutputCapacitorSelectionsection forthecalculationofCOUTandESRCOUT. TheRMSripplecurrentratingoftheoutputcapacitors indiscontinuousoperationcanbedeterminedusingthe followingequation: I I D RMS COUT DISCONTINUOUS O MAX ( ), ( ) • ( • ) • ≥ − 4 3 2 3 DD2 Flyback Converter: Input Capacitor Selection Theinputcapacitorinaflybackconverterissubjectto alargeRMScurrentduetothediscontinuousprimary current.Topreventlargevoltagetransients,usealow ESRinputcapacitorsizedforthemaximumRMScurrent. TheRMSripplecurrentratingoftheinputcapacitorsin discontinuous operation can be determined using the followingequation: I P V RMS CIN DISCONTINUOUS OUT MAX IN MIN ( ), ( ) ( ) • ≥ h •• ( • ) • 4 3 3 − D D MAX MAX SEPIC CONVERTER APPLICATIONS TheLT3757canbeconfiguredasaSEPIC(single-ended primaryinductanceconverter),asshowninFigure1.This topologyallowsfortheinputtobehigher,equal,orlower thanthedesiredoutputvoltage.Theconversionratioas afunctionofdutycycleis: V V V D D OUT D IN + = − 1 incontinuousconductionmode(CCM). InaSEPICconverter,noDCpathexistsbetweentheinput andoutput.Thisisanadvantageovertheboostconverter forapplicationsrequiringtheoutputtobedisconnected fromtheinputsourcewhenthecircuitisinshutdown. Comparedtotheflybackconverter,theSEPICconverter hastheadvantagethatboththepowerMOSFETandthe outputdiodevoltagesareclampedbythecapacitors(CIN, CDCandCOUT),therefore,thereislessvoltageringing acrossthepowerMOSFETandtheoutputdiodes.The SEPICconverterrequiresmuchsmallerinputcapacitors thanthoseoftheflybackconverter.Thisisduetothefact |
|
Link URL |
| Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Link do karty katalogowej | Linki | Lista producentów All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Polish ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
