 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
SP7661 Datasheet(PDF) 11 Page - Sipex Corporation |
|
||||||||||||||||||||||||||||||
SP7661 Datasheet(HTML) 11 Page - Sipex Corporation |
|
|
11 / 20 page  Nov3-06 Rev I SP766 Wide Input Voltage Range 3A, 600kHz Buck Regulator © 2006 Sipex Corporation APPLICATIONS INFORMATION Output Capacitor Selection TherequiredESR(EquivalentSeriesRe- sistance)andcapacitancedrivetheselec- tionofthetypeandquantityoftheoutput capacitors.TheESRmustbesmallenough thatboththeresistivevoltagedeviationdue toastepchangeintheloadcurrentand the output ripple voltage do not exceed thetolerancelimitsexpectedontheoutput voltage. During an output load transient, theoutputcapacitormustsupplyallthead- ditionalcurrentdemandedbytheloaduntil theSP7661adjuststheinductorcurrentto thenewvalue. InordertomaintainVOut,thecapacitance must be large enough so that the output voltageisheldupwhiletheinductorcur- rent ramps to the value corresponding to the new load current.Additionally, the ESRintheoutputcapacitorcausesastep intheoutputvoltageequaltothecurrent. Becauseofthefasttransientresponseand inherent100%to0%dutycyclecapability providedbytheSP7661whenexposedto outputloadtransients,theoutputcapacitor istypicallychosenforESR,notforcapaci- tancevalue. TheESRoftheoutputcapacitor,combined withtheinductorripplecurrent,istypically themaincontributortooutputvoltageripple. ThemaximumallowableESRrequiredto maintainaspecifiedoutputvoltageripplecan becalculatedby: ReSr ≤ ∆VOut IPk-Pk where: ∆VOut = Peak-to-Peak Output Voltage Ripple IPk-Pk = Peak-to-Peak Inductor Ripple Current Thetotaloutputrippleisacombinationof theESRandtheoutputcapacitancevalue andcanbecalculatedasfollows: ∆VOut = √(IPP•(1–D))2+(IPP•ReSr)2 ƒs•COut ƒs=SwitchingFrequency D=DutyCycle COut = Output Capacitance Value Input Capacitor Selection Theinputcapacitorshouldbeselectedfor ripple current rating, capacitance and volt- agerating.Theinputcapacitormustmeet theripplecurrentrequirementimposed bytheswitchingcurrent.Incontinuous conductionmode,thesourcecurrentof thehigh-sideMOSFETisapproximatelya squarewaveofdutycycleVOut/ViN.More accurately,thecurrentwaveformistrap- ezoidal,givenafiniteturn-onandturn-off, switchtransitionslope.Mostofthiscurrent issuppliedbytheinputbypasscapaci- tors.TheRMScurrenthandlingcapability oftheinputcapacitorsisdeterminedat maximumoutputcurrentandunderthe assumptionthatthepeak-to-peakinductor ripplecurrentislow,itisgivenby: ICiN(rMS) = IOut(MAx) • √D(1 - D) Theworstcaseoccurswhenthedutycycle Dis50%andgivesanRMScurrentvalue equaltoIOUT/2.Selectinputcapacitorswith adequateripplecurrentratingtoensurereli- ableoperation. Thepowerdissipatedintheinputcapaci- toris: PCiN = I 2 CiN(rMS) • reSr(CiN) Thiscanbecomeasignificantpartofpower lossesinaconverterandhurttheoverall energy transfer efficiency. The input volt- agerippleprimarilydependsontheinput |
Similar Part No. - SP7661 |
|
Similar Description - SP7661 |
|
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
