Under The Hood Of Flyback SMPS Designs PPT Presentation
Power Supply Design SeminarTopic 1 Presentation:Under the Hood of FlybackSMPS DesignsReproduced from2010 Texas Instruments Power Supply Design SeminarSEM1900, Topic 1TI Literature Number: SLUP254 2010, 2011 Texas Instruments IncorporatedPower Seminar topics and online powertraining modules are available at:power.ti.com/seminars
Topic 1Under the Hood ofFlyback SMPS DesignsJean PicardSLUP254
Agenda1. Basics of Flyback Topology2 Impact of Transformer Design on Power Supply2.Performance3. Power Supply Current Limiting4. SummaryTexas Instruments—2010 Power Supply Design Seminar1-2SLUP254
Transfer of Energy FET turns ON– Voltage across primarymagnetizing inductance Vi EEnergy iis storedtd ini flybackfl b ktransformer: Function of L,D and Ts– Secondaryy diode in blockingg stateIPIo Vi1:n2– During commutation: Leakageenergy absorbed by clamp circuit– Stored energy transferred to outputthrough diode– If DCM operationoperation, all the storedenergy is transferredClaamp FET turns OFFIP- VoIoutVdrain Pulsating input and outputcurrenttTexas Instruments—2010 Power Supply Design Seminar1-3SLUP254
Transfer of Energy FET turns ON– Voltage across primarymagnetizing inductance Vi Energy is stored in flybacktransformer: Function of L, D and TsIPIo– Secondary diode in blocking state VVi– During commutation: Leakageenergy absorbed by clampcircuit– Stored energy transferred tooutput through diode– If DCM operationoperation, all the storedenergy is transferredIo1:n2Clammp FET turns OFFIP -VoIoutVdrain Pulsating input and outputcurrenttTexas Instruments—2010 Power Supply Design Seminar1-4SLUP254
Transfer of Energy FET turns ONO– Voltage across primarymagnetizing inductance Vi Energy is stored in flybacktransformer: Function of L, D and TsIPIo– Secondary diode in blocking state Vi– During commutation: Leakageenergy absorbed by clamp circuit– StoredStd energy transferredtfd totoutput through diode– If DCM operation, all the storedenergy is transferred1:n2Clamp FET turns OFFOIo -VoIoutVdrain Pulsating input and outputcurrentTexas Instruments—2010 Power Supply Design Seminar1-5SLUP254
Transfer of Energy FET turns ON– Voltage across primarymagnetizing inductance Vi Energy is stored in flyback transformer:Function of L, D and Ts Vi1:n2 FET turns OFF– During commutation: Leakage energyabsorbed by clamp circuit– Stored energy transferred to outputthrough diode– If DCM operation, all the storedenerg is transferredenergyClamp– Secondary diode in blocking stateVoIoutVdrain Pulsating input and output currentTexas Instruments—2010 Power Supply Design Seminar1-6SLUP254
CCM versus DCM Continuous conduction mode (CCM)– Small ripple and rms current– Lower MOSFET conduction andturn-off loss– Lower core loss– Lower capacitors loss– Can have better “full load” efficiency– SmallerS ll EMI andd outputt t filtersfilt Discontinuous conduction mode(DCM)– No diode reverse recovery loss– Lower inductance value May result in a smaller transformer– Better “nono loadload” efficiency– First-order yCurrentIoVon2 ViIpkIpkminΔILΔILSS(1 – D) x Tsm2SIo avggTime (t)TsVdrainPrimaryMOSFETD TsVon2 ViViIpkPrimaryCurrentIP(1 – D) TsIdlePeriod Inherently stable– No RHPZ pproblem– Slope compensation not neededin CMCD x TsTSecondaryCurrentIoTexas Instruments—2010 Power Supply Design SeminarIo avgTime (t)1-7SLUP254
Right-Half-Plane Zero, CCM OperationCllamp– Effect of control action during ONtime is delayedy until next switchturn OFF– Phase decreases with increasinggainf RPHZ (1 D )2IP- VoIout Vdrain Initial reaction is in oppositedirection of desired correction RHP Zero1:n2FET ON Vi Vo2πL D Iout n 22D MainM i switchit h dduty-cycletlTexas Instruments—2010 Power Supply Design Seminar1 21:nClamp Energy is delivered during 1 – D ViIo -VoIoutVdrainFET OFF1-8SLUP254
RCD Clamp Circuit During commutation primary-toprimary tosecondary, the leakage energyis absorbed by the clamp circuit–Rc la m p – Rclamp dissipates the leakageenergy and some magnetizingenergy Vi– The clamp capacitor ensures alow voltage rippleDiode orSynchronousN1:N2 RectifierVc la m pIPVdra in– Use short connection withminimum loop area Vclamp is maximum at full loadand minimum input voltage– Rclamp selected for a maximumdrain voltage in worst case– Tradeoff between efficiency,peak drain voltage, outputcurrent limit and cross regulation(see ringing effect)VoRSClamp-DiodeForward RecoveryVi Vc la m pVdra inPrimaryMOSFETTexas Instruments—2010 Power Supply Design SeminarLeakage-InductanceDemagnetizationVi Von1-9SLUP254
Agenda1. Basics of Flyback Topology2 Impact of Transformer Design on Power2.Supply Performance3. Power Supply Current Limiting4. SummaryTexas Instruments—2010 Power Supply Design Seminar1-10SLUP254
Transformer’s Leakage Inductance Transformer’sTransformer s leakageinductance represented by Lleak2– Primary winding is the closest tocenter gap––Vi ClampVmag1 IP Voltage spike on FET duringcommutation Rate of rise of current isinfluenced byy leakageg inductance Commutation primary-tosecondary is not instantaneouspon Vclampand dependsLm Vleak2 –Vmag2ISVD–During Primary-toSecondary Commutationø Vout–W1FETW2 When FET turns OFF– Lleak2 opposes to IP decrease andIS increase– Magnetizing inductance works tomaintain magnetizing currentLleak2N1:N2Clamp DiodeForward RecoveryLeakageInductanceDemagnetizationCurrent Circulates inSecondaryy Winding(s)g( )Vi VclampVclampVFETLeakage InductanceResonates with DrainCapacitanceVi VclampVFETClClampCCapacitorit VoltageV ltVmag2ClampCapacitorVoltage0VVmag2 – VD – VoutVleak2IPReduction in Magnetizing CurrentDue to Faster CommutationIPISISDtr– Loss of volt-secondsLost Volt-SecondsLow Clamp VoltageTexas Instruments—2010 Power Supply Design SeminarDtrHigh Clamp Voltage1-11SLUP254
Effects of Leakage Inductance Clamp circuits and snubbers needed for primary FET andsecondary rectifier(s) Lower power-supply efficiency Impactpon ggate-drive strategygy if synchronousyrectifier isused Highergdutyy cycleyand magnetizinggg current than expectedp Higher H-field radiated emission HighHi h iimpactt on cross-regulationl tiTexas Instruments—2010 Power Supply Design Seminar1-12SLUP254
How Leakage Can Be Minimized Leakage inductance is a function of winding geometrygeometry, number of turnsand separation between primary and secondary– Minimize the separation between the primary and main secondarywinding(s)– Interleave the primary and main secondary– Select a core with a long and narrow windowLLW2W1W2W1W1W2W2W1W1W2W1W2W1W2W2W1Option 1Option 2 Leakage inductance is not lowered with a high permeability core Having the winding tightly coupled to the core will not reduce itTexas Instruments—2010 Power Supply Design Seminar1-13SLUP254
Cross-Regulation – Overview Multiple-output flyback topology is popular because of itssimplicity and low cost If the coupling is perfect, the turns ratio directly definesoutput voltages In the real world, “perfect” coupling is not possible This often results in poor cross-regulationTexas Instruments—2010 Power Supply Design Seminar1-14SLUP254
Cross-Regulation Physical Model Transformer windings cannot all be equally well coupled tothe gap because of physical separation between them Magnetic energy stored between the windings representedas leakage inductances Model not applicable to any transformer geometry CCan bbecome complexl if iinterleavingt li iis used,d or if multiplelti lsecondary windings are wound simultaneously (multifilar) Not accurate in situation of lightly loaded secondary outputs Good tool to understand how the common flybacktransformer geometries workTexas Instruments—2010 Power Supply Design Seminar1-15SLUP254
Cross-Regulation Physical ModellW4 Vi–Clamp V3–lW2 V2– N1:N2W4WN3W3WlpW2WlW3W1WPrimary V4–N4FETBasic Flyback Circuitlp–Vi Clamp Lleak12Vmag1 LmTransformer 1:N2FET V2– V3– V4–Transformer Physical Model This circuit is only applicable to the transformer windings stackup shown Each leakage inductance considered is between two consecutive secondaries Also called “Ladder model”Texas Instruments—2010 Power Supply Design Seminar1-16SLUP254
Flux Lines during CommutationEach Secondary Winding with Nominal Load φm decreases during commutationφm dφ/dt (decreasing) in each secondarywindingd g iss limitedted by itsts output voltageo tage– Increasing currentinduced in W2 toW4 to maintainφm in the gape N W2dφ mdtW1W3 W4L Leakage between W2 and W1– W1’s voltage limited by clamp W1 closest to gapDuring Primary-to-Secondary CommutationCurrent in All Windings– Vclamp limits dφm/dt in the gap duringcommutation W2 is next to W1– W2 limits the dφ/dt seen by W3 and W4– W3 and W4 output voltage lower thanwithout leakage Current commutates progressively fromnear to remote secondary windingsTexas Instruments—2010 Power Supply Design SeminarlpI2I3I4Secondary Currents DuringCCommutationt ti BasedBd on PhysicalPh i l ModelM d l1-17SLUP254
Ringing Effect HighHi h dV/dt whenh maini switchit h tturns offff if maini outputt t iis hheavilyil lloadedd d Transformer leakage inductance and parasitic capacity auxiliarysecondaryy voltageg tends to “ring”g If auxiliary output fully loaded this ringing is clamped If lightly loaded voltage overshoot with peak detector effect Much higher (sometimes 2 x nominal value!) auxiliary output voltage atlight load– Primary clamp voltage has high impact on result Most existing transformer models fail to predict this This effect can be mitigated (but not eliminated)– Minimize leakage inductance between secondary windings– Locate the highest power secondary(ies) closest to the primary Other solutions include a post-regulator, series resistor or minimum loadTexas Instruments—2010 Power Supply Design Seminar1-18SLUP254
Cross-Regulation ExampleAuxiliary Output Lightly Loaded W2 (high current output) heavily loaded,W4 lightly loaded– W4’s output received too much energygy duringgPhase 1 due to ringing– W2’s output did not receive enough energy At end of commutation ((Phase 1):)– Σ{reflected secondary currents} Ù magnetizingcurrent V4 went too highg– Phase 2: high dφ/dt (decreasing) in W4 IW4 0 A rapidly– IW2 increases to maintain φm in the gap After IW4 crosses 0 A, W2’s and W3’s di/dtchange to maintain the downslope of themagnetizing current and fluxφmH δ δ N IA μTexas Instruments—2010 Power Supply Design SeminarI4 pkIW4I3 pkIW3Effect of V3Capacitors ESRV3I2 pkIW2Vmag1IP pkIPPhase1Phase2Phase3Time (t)φmW2W1W3 W4Phase 2: No Primary Current1-19SLUP254
Test Results10 ΩR W3VD DVAW3W3( 9T)W4( 14T)300 ΩW4W3W6W236 ΩW1BW6(9T)V6R66.8 µFCurrentProbeIW4Current TransformerV IprimV I100 1100:1W1ACurrent ProbeIW6V46.8 µF ViR c la m p15 kΩ0.1 µFVc la m pMURS1205VW1( 21T)IPW2( 4T)IW2Primary MOSFET Input voltage: 48 VCurrent Transformer1:100V Is e c6.8 Ω249 ΩI5To CS InputVTo 5-V Filterand LoadSyncRectifier 5-V5 V outputt t load:l d 0 A tot 5A Auxiliary outputs:V6 ((10 V at 0 to 140 mA)) andV4 (18 V at 0 to 200 mA)R4 Switching frequency: 250 kHz Primary magnetizinginductance: 70 µHTexas Instruments—2010 Power Supply Design Seminar1-20SLUP254
Cross-Regulation Test Results withp Fullyy LoadedMain OutputIW6(0.5 A/div)2IW4 (1 A/div)IW6 (0.5 A/div)2IW4 (1 A/div)44IW2(2.94 A/div)IW2(2.94 A/div)11Time (0.5 µs/div)Time (0.5 µs/div)V6 at 11.66WW, V4 at 22.55WW,I5 V 5 AV6 at 00.55WW, V4 at 33.66WW,I5 V 5 A The two auxiliary outputs operate in DCM Notice the change of slope of IW2 when IW4 or IW6 crosses 0 ATexas Instruments—2010 Power Supply Design Seminar1-21SLUP254
Cross-Regulation Test Results: Lightly LoadedAuxiliaryy with Main Outputp Fullyy LoadedI5 V 5 A,V4 at 0.3 W,Vclamp 70 VV6 (10 V/div)12.4 VI5 V 5 A,V4 at 0.3 W,Vclampp 70 VV6 (10 V/div)20.6 VVW6(10 V/div)V/di )VW6(10 V/div)IW6(200 mA/div)Time ((1 µµs/div))V6 at 0.5 WTime ((1 µµs/div))V6 at 5 mW At minimum load,load V6 (10 V nominal) goes up to 20.620 6 VTexas Instruments—2010 Power Supply Design Seminar1-22SLUP254
Cross-Regulation Test Results with Main OutputFully Loaded : Impact of Clamp VoltageI5 V 5 A,V4 at 0.3 W,Vclamp 83 VV6 (10 V/div)14.4 VI5 V 5 A,V4 at 0.3 W,V6 (10 V/div)26 VVclamp 83 VlVW6(10 V/div)V/di )VW6(10 V/div)IW6(200 mA/div)Time (1 µs/div)Time (1 µs/div)V6 at 0.5 WV6 at 5 mW RCD resistor has been increased for higher Vclamp: 70 V 83 V V6 increased significantly in both casesTexas Instruments—2010 Power Supply Design Seminar1-23SLUP254
Overload Test at Auxiliary Output:pof LeakagegImpact There was no hiccupmode even at morethan 3 A! ThThe overloadedl d d windingi diis unable to take all theenergy because ofleakage W3 having inleakage,fact a better coupling toprimary than W6IW4 (1 A/div)I5 V 0 A,V4 at 2.5 W,R6 1 Ω43VAW3 (20 V/div)IW6 (2 A/div)6.2-A Peak2– Enough energydelivered by W3 to VDDto maintain switchingTexas Instruments—2010 Power Supply Design SeminarTime (0.5 µs/div)1-24SLUP254
Benefits of Good Cross-Regulation Good control of auxiliary outputs in spite of load variations Better control of gate drive voltage amplitude,amplitude less gatedrive losses Lower rms current in output capacitors, lower dissipation May allow the controller to reach hiccup mode more easilywhen the main output is short-circuited for better protection– Not necessarily true if the short-circuit is applied to an auxiliaryoutput!Texas Instruments—2010 Power Supply Design Seminar1-25SLUP254
How Cross-Regulation can be Improved The high current winding must have the best coupling to primary Minimize leakage between all secondary windings Optimize,p, not minimize,, the leakageg inductance of auxiliaryy windingsg to pprimaryy Use winding placement to control leakage inductanceW3Primary BW2BW2APrimary APrimary BW2BW3W2APrimary AW3W2BPrimary BW2APrimary A– Winding stackup– Spread each winding over the full width of the bobbin for better couplingIf W3 is lightlyloaded and W2Betteroris the highthancurrent mainoutput. Operate main output in CCM Try to avoid operating the auxiliary outputs in DCM. In some cases, considerusing resistance in series with the diode Consider winding more than one auxiliary secondary simultaneously (multifilar) Lower clamp voltage may help– Trade-off between cross regulation, efficiency, peak drain voltage and current limit– Some other types of clamp circuits may provide better results than the RCD clampTexas Instruments—2010 Power Supply Design Seminar1-26SLUP254
Impact of Transformer Design on Flyback Efficiency Multifilar or Litz wires when necessaryy Interleaving Select core shape for minimum number of layers– Optimize the transformer turns ratio forbest efficiency– Select CCM operation300275250Secondary RMSCurrent Squaredat 48 V225200175200Good Duty-CycleTrade-Off with48-V Inputp150125100100755020 x Primary RMSCurrent Squared at 48 V2500204060Duty Cycle ( %)802Secondary RMSS Curr ent Squaredd (A )– Minimize leakage inductance from primaryto main (high(high-current)current) secondary– Minimize transformer high frequencyconduction loss20x Primar y RMMS Current Squaredd (A2) ThThe followingf ll i guidelinesid lican beb usedd duringd i ttransformerfdesign to optimize the converter efficiency3000100 Other factors also have an indirect impact on efficiency– Cross-regulation VDD rail used for gate drive Output capacitors rms current– Impact of fringing flux from gap Worse with planar transformersTexas Instruments—2010 Power Supply Design Seminar1-27SLUP254
Flyback and EMIISIPN1:N2 ICM–– ViPrimmary A– Shields Vdrain E-field– ReducesR diinterwindingti di capacityit effectff t on CE Minimize leakage for low H-field RE Center-gap transformerTexas Instruments—2010 Power Supply Design Seminar Output toChassis CM Better to start with end connected to primaryMOSFET Interleaving reduces H-field RE but may increaseeffectiveff ti PP-SS iinterwindingti di capacitanceitVoutVDFET2– Less if facing windingsindings at same ACpotential– Diode versus synchronous rectifier– Flyback ForwardClampOther Secondaryy Transformer and diode configurationimpact effective capacitanceIDMSeconndary BVi–SSeconndary A Interwinding capacitance CM CEPPrimmary C– Use low Z caps, minimize loop areas– Output filter often requiredICM2Primmary B Flyback IP and IS pulsate–FETVDVout 1-28SLUP254
Agenda1. Basics of Flyback Topology2 Impact of Transformer Design on Power Supply2.Performance3. Power Supply Current Limiting4. SummaryTexas Instruments—2010 Power Supply Design Seminar1-29SLUP254
Power Supply Current Limiting – Overview Current-limiting characteristic of power supplydefines:– Output power beyond which output voltage falls outof regulation. Corresponds to the “output load-currentli it” (Iout LIM)limit”– Output current in overload situations including short-circuitsshort circuits Current-limiting characteristic is influenced byparasitics– Turn-off delays, leakage inductance, Texas Instruments—2010 Power Supply Design Seminar1-30SLUP254
Understanding Current Limit –Flyback Power Supply with Peak CMC in CCM ViPower Supply Controller–PWMCOMP((From ErrorAmp) VC LIMVoIoutPrimaryCurrentD x TsRSCSecondaryCurrentRI SENSEVCIoClampSlope CompClock Ramp1:n2CRsΔILIA LIMIpk LIMm2SI o avg(1 – D) x TsTime (t)Just at Current Limit, Output Beginsto Fall Out of RegulationCurrentSenseFilter Ipk LIM isi ththe primaryipeakkcurrent limit Io avgp currento avg is the output If short-circuit, Io avg can bemuch higher than whencurrent limit has just beenreachedIpk LIMPrimaryCurrentD x TsSecondaryCurrentI o avg(1 – D) x TsTime (t)Output Short CircuitIout Io avg Texas Instruments—2010 Power Supply Design SeminarIA (1 D )n21-31SLUP254
Current-Limit Model – Basic Representation Peak CMC in CCM, fixed switching frequencyI pk m2m1ΔILVCRSIA (AverageMagnetizingCurrent))D TsGate ControlNeglecting DC voltage drops:VoΔI L m2 (1 D ) TS n 2 LTexas Instruments—2010 Power Supply Design SeminarVoD n 2 Vi Vo1-32SLUP254
Influence of Input DC Voltage on Output LoadCurrent Limit – Impact of FeedforwardPower Supply ControllerPWMCOMP(From ErrorAmp) Io10VoIoutClampSlope CompClock Ramp–1:n2RSCRI SENSEVCCRsVC LIMOutput Loaad Current L imit (A) ViRffFeedforwardIf Vi (1 – D) Iout LIM increases9Without Feedforward87With Feedforward65202530354045Input Voltage(V)5055 With feedforward, output load current limit becomes almost independent ofinput voltage Better control during overload, less stress on power circuitry Power limit CostC t and/ord/ sizei reductiond ti Feedforward also improves line noise rejectionTexas Instruments—2010 Power Supply Design Seminar1-33SLUP254
Current Limit Model – With FeedforwardVCK ff V iR S I pkRS m 2RS ggMagnetizingCurrent)RS m1RS I AD TsGate Control Kff x Vi is the feedforward contribution– Subtracting it from Vc is identical to adding it to current feedbackTexas Instruments—2010 Power Supply Design Seminar1-34SLUP254
Current Limit Model – Adding Slope CompensationSlope Compensation(Clock Ramp)–m0 x(Ts Tdis)2m0K ff V iVCRS I ARS m2RS IL pk m inD Ts2R S m1TdisD TsGate Control Slope compensation to avoid subharmonic oscillation at duty-cycleduty cycle close to orhigher than 50% For easier understanding, slope compensation contribution subtracted from Vc.– Equivalent to slope compensation added to current feedback– In that circuit representation, the slope compensation is capacitively-coupledTexas Instruments—2010 Power Supply Design Seminar1-35SLUP254
Current Limit Model – With all Delays, SlopeCompensationpand Feedforward For a more accurate, parasitics must be included in theanalysis Parasitic delays– RC filter time delay– Turn off delay, including current comparator and gate drive– FET turn-on delay from onset of slope compensation ramp See Topic 1, Appendix A, in the Seminar Manual fordetailed equationsTexas Instruments—2010 Power Supply Design Seminar1-36SLUP254
Influence of Transformer Leakage onOutputp Load Current Limit Rate of rise of current is influencedby leakage, commutation primary-tosecondary is not instantaneous Loss of volt-seconds (also influencedby the clamp voltage) Duty-cycle and average magnetizingcurrent have to increase to maintainthe output voltagegconduction loss Higher Higher transformer peak current thanexpected- Iout LIM lower than expected Leakage inductance helpshowever to keep control ofthe output current in outputshort-circuit situation–Vi Clamp–Ideal Xfmr Lleak2N1:N2 Vleak2 – –Vmag1 IPLmVmag2VD Vout–FETIPISLost Volt-SecondsVi D new Vclamp D tr Texas Instruments—2010 Power Supply Design Seminar ISDtrVo (1 D new D tr )n21-37SLUP254
Current Limit During Overload – Example withCombined Effects– Short-circuit: output currentmuch higher than at onset ofcurrent limit Parasitic turn off delays mayresult in an out of controlcurrent if volt-secondsbalance is not possible at thetransformer– Transformer’s leakagei d tinductancehhelpsl tto maintaini t ithat balance– If no leakage, the imbalanceoccurs startingg at Vo1– With leakage, the imbalanceoccurs only from Vo2Assuming no hiccup mode25Outpuut Current (A) In overload: Output currentincreases output voltagedecreases20Without LeakageWith Leakage1510554.5Vo shortn2Texas Instruments—2010 Power Supply Design Seminar4(3.532.521.5Output Voltage (V)10.50Vo1 Vo2Short Circuit) TS t del OFF D tr TS Vi t del D tr TSd l OFF Vclampl1-38SLUP254
Summary ThThe flflybackb k power ttransformerfiis ththe kkey elementlt off ththeconverter, for optimum efficiency and cross-regulation Parasitics hahavee a strong inflinfluenceence on flflybackback conconverter’serter’sbehavior, particularly under overload or short-circuitconditions The primary clamp circuit design is a trade-off between:––––EfficiencyPeak drain voltageOutput current limitCross regulationCross-regulation Simple feedforward technique can be used to optimize theconverter and the system, lowering worst-caseworst case componentsstress and reducing the overall cost and sizeTexas Instruments—2010 Power Supply Design Seminar1-39SLUP254
TI Worldwide Technical SupportInternetTI Semiconductor Product Information Center Home Pagesupport.ti.comTI E2E Community Home Pagee2e.ti.comProduct Information CentersAmericas Phone 1(972) tional al 91-80-41381665DomesticToll-Free Number Note: Toll-free numbers do not supportmobile and IP phones.Australia1-800-999-084China800-820-8682Hong w 6-0010Fax 8621-23073686Email tiasia@ti.com or htmFaxInternet/Email 1(972) 927-6377support.ti.com/sc/pic/americas.htmEurope, Middle East, and AfricaPhoneEuropean Free CallInternationalRussian Support00800-ASK-TEXAS(00800 275 83927) 49 (0) 8161 80 2121 7 (4) 95 98 10 701 Note: The European Free Call (Toll Free) number is not activein all countries. If you have technical difficulty calling the freecall number, please use the international number above.FaxInternetDirect Email (49) (0) 8161 80 nternet/Email icwww.tij.co.jp/picImportant Notice: The products and services of Texas InstrumentsIncorporated and its subsidiaries described herein are sold subject to TI’sstandard terms and conditions of sale. Customers are advised to obtain themost current and complete information about TI products and servicesbefore placing orders. TI assumes no liability for applications assistance,customer’s applications or product designs, software performance, orinfringement of patents. The publication of information regarding any othercompany’s products or services does not constitute TI’s approval, warrantyor endorsement thereof.A122010The platform bar and E2E are trademarks of Texas Instruments. All other trademarksare the property of their respective owners.SLUP254
IMPORTANT NOTICETexas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,and other changes to its products and services at any time and to discontinue any product or service without notice. Customers shouldobtain the latest relevant information before placing orders and should verify that such information is current and complete. All products aresold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standardwarranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except wheremandated by government requirements, testing of all parameters of each product is not necessarily performed.TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products andapplications using TI components. To minimize the risks associated with customer products and applications, customers should provideadequate design and operating safeguards.TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Informationpublished by TI regarding third-party products or services does not constitute a license from TI to use such products or services or awarranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectualproperty of the third party, or a license from TI under the patents or other intellectual property of TI.Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompaniedby all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptivebusiness practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additionalrestrictions.Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids allexpress and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is notresponsible or liable for any such statements.TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonablybe expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governingsuch use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, andacknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their productsand any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may beprovided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products insuch safety-critical applications.TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products arespecifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet militaryspecifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely atthe Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products aredesignated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designatedproducts in automotive applications, TI will not be responsible for any failure to meet such requirements.Following are URLs where you can obtain information on other Texas Instruments products and application oCommunications and Telecom mComputers and Peripheralswww.ti.com/computersData Convertersdataconverter.ti.comConsumer Electronicswww.ti.com/consumer-appsDLP Productswww.dlp.comEnergy and w.ti.com/industrialClocks and Logiclogic.ti.comSpace, Avionics and Defensewww.ti.com/space-avionics-defensePower Mgmtpower.ti.comTransportation and Automotive er.ti.comVideo and ImagingRFIDwww.ti-rfid.comOMAP Mobile Processorswww.ti.com/omapWireless Connectivitywww.ti.com/wirelessconnectivityTI E2E Community Home Pagewww.ti.com/videoe2e.ti.comMailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265Copyright 2011, Texas Instruments Incorporated
–Secondary diode in blocking state O V Io FET turns FF –During commutation: Leakage energy absorbed by clamp circuit St d t f dt 1:n2 i Vo m p I Io –Stored energy transferred to output through diode –If DCM operation, all the stored energyistransferred Cla Vdrain-out energy is transferred Pulsating input andoutput current
May 02, 2018 · D. Program Evaluation ͟The organization has provided a description of the framework for how each program will be evaluated. The framework should include all the elements below: ͟The evaluation methods are cost-effective for the organization ͟Quantitative and qualitative data is being collected (at Basics tier, data collection must have begun)
Silat is a combative art of self-defense and survival rooted from Matay archipelago. It was traced at thé early of Langkasuka Kingdom (2nd century CE) till thé reign of Melaka (Malaysia) Sultanate era (13th century). Silat has now evolved to become part of social culture and tradition with thé appearance of a fine physical and spiritual .
On an exceptional basis, Member States may request UNESCO to provide thé candidates with access to thé platform so they can complète thé form by themselves. Thèse requests must be addressed to esd rize unesco. or by 15 A ril 2021 UNESCO will provide thé nomineewith accessto thé platform via their émail address.
̶The leading indicator of employee engagement is based on the quality of the relationship between employee and supervisor Empower your managers! ̶Help them understand the impact on the organization ̶Share important changes, plan options, tasks, and deadlines ̶Provide key messages and talking points ̶Prepare them to answer employee questions
Dr. Sunita Bharatwal** Dr. Pawan Garga*** Abstract Customer satisfaction is derived from thè functionalities and values, a product or Service can provide. The current study aims to segregate thè dimensions of ordine Service quality and gather insights on its impact on web shopping. The trends of purchases have
Jeep Cherokee 14-21 under seat, DS 60 psi under hood, DS n/a Compass 11-17 under seat, DS 60 psi under hood, DS n/a Gladiator 20-21 under seat, DS 60 psi under hood, DS n/a Grand Cherokee 10-21 under seat, DS 60 psi under hood, DS n/a Liberty 08-12 under seat, DS or PS 60 psi under hood, DS n/a Patriot 11-17 under seat, DS 60 psi under hood, DS n/a
A representative flyback converter can be seen in Figure 3. Figure 3. A Simplified Schematic of a Flyback Converter CONTROL Vin T Q Ipri Vout D The power switch essentially places the primary inductance of the flyback transformer across the input voltage source when it is turned
winding and then decays back down in the secondary winding during the flyback interval. Thus, when designing the flyback transformer and assessing the losses, you must consider it more of an inductor than a transformer. Flyback operation Figure 2 shows the different operating phases of the fly
