A6217Design-Tool设计工具

15876715834122020/4/23ComponentCalculatorDescriptionSymbolValueUnitRemarkInputsupplyvoltageVin12VLEDcurrentrequiredi_LED2ANumberofLEDsinoutputstringN2ForwardvoltageofeachLEDV_f3VRipplecurrentas%ofaveragecurrent20%typically20-40%ofi_LEDForwardvoltagedropofschottkydiodeVd0.5Vtypically0.4-0.7VDesiredswitchingfrequency2.00MHzDescriptionSymbolValueUnitRemarkSenseresistoraveragevoltage(typ.0.2V)Vs0.2VOutputLEDstringvoltageVout6.2VIncludingsensevoltageof~0.2VCalculateddutyCycleD53.6%D=(Vo+Vd)/(Vi+Vd)EstimatedLEDripplecurrent0.4Apk-pkMin_T_on(worst-case0.10us)0.1uSMin_T_off(worst-case0.15uS)0.15uSFrequencyselectionconstantk0.014freq=1/(k*(Ron+6))+0.09CalculatedsenseresistorvalueRs_cal0.100ΩRs=Vs/i_LEDEnterpreferredsenseresistorvalueRs0.400ΩCalculatedLEDcurrenti_LED0.500Ai_LED=Vs/RsCalculatedTonselectionresistor31.4kOhmRon=1/((f_sw-0.09)*k)-6EnterpreferredresistorvalueRon31.4kΩActualswitchingfrequencyf_sw2.00MHzCalculatedSWon-timeTon0.268uSTon=1/fsw*DCalculatedSWoff-timeToff0.232uSToff=1/f_sw-TonCalculatedinductorvalue3.9uHL=(Vin-Vout)*Ton/i_rippleEnterpreferredinductorvalue,LL3.9uHCalculatedripplecurrenti_ripple0.400AMinimuminductorcurrentratingi_sat0.840AIncluding20%headroomCalculatedripplevoltageV_ripple0.160Vpk-pkKeepripplevoltage=0.02VSwitchingfrequency2.00MHzAverageLEDcurrentwithRs=.4Ω0.500ALEDripplecurrentwithL=3.9uH0.400Apk-pkRipplecurrentas%ofaveragecurrent80%InputVoltageVin12VfromprevioussectionThermalResistanceR_θJA35°C/WSOIC-8pn4-layerPCBSWon-restsianceat25°CR_DSON0.4Ω0.25typ,0.4maxResistanceincreaseathot50%40%at100°C,60%at125°COutputLEDstringvoltageVout6.2VfromprevioussectionCalculateddutyCycleD53.6%D=(Vo+Vd)/(Vi+Vd)CalculatedLEDcurrenti_LED0.5AfromprevioussectionSWConductionLossP_cond0.08Wi^2*R*DSwitchingfrequencyf_sw2MHzfromprevioussectionSWrisetimeT_rise5nS5nStypicalfromSWwaveformSWfalltimeT_fall10nS10nstypicalSWswitchinglossP_sw0.09WVin*iout*(t_r+t_f)/2*f_swInputcurrentforVccbiassupplyi_IN2.5mAtypically2.5mAPowerforVccbiassupplyP_bias0.03WVin*i_INPerformancesummarywithpreferredvaluesPowerLossCalculation(forIConly)A6217ExternalComponentValueCalculator(LastupdatedAug30,2016)Notes:1.Entersystemdataintowhitecells.2.Aftercomponentvaluesarecalculated,thenenterpreferredvaluesintocellswithBluetext3.Aperformancesummaryisthengenerated(Greentext).4.Warningmessages,ifany,arelistedbelowinRed