Electronic Components Datasheet Search
 ALLDATASHEET.COM Part #DescriptionMarking X

## ADP1871 Datasheet(HTML) 30 Page - Analog Devices

 30 / 44 pageADP1870/ADP1871Rev. 0 | Page 30 of 44Assuming an overshoot of 45 mV, determine if the outputcapacitor that was calculated previously is adequate:ZEROCOMPCOMPfRCπ=21=331025.61010014.321×××××= 250 pF()()2226222)8.1()mV458.1()A15(101)()(−−××=−Δ−×=−OUTOVSHTOUTLOADOUTVVVILC= 1.4 mFLoss CalculationsDuty cycle = 1.8/12 V = 0.15RON (N2) = 5.4 mΩChoose five 270 μF polymer capacitors.tBODY(LOSS) = 20 ns (body conduction time)The rms current through the output capacitor isVF = 0.84 V (MOSFET forward voltage)A49.1V2.13V8.110300μF1)V8.1V2.13(3121)(31213,,=×××−×=××−×=MAXINOUTSWOUTMAXINRMSVVfLVVICIN = 3.3 nF (MOSFET gate input capacitance)QN1,N2 = 17 nC (total MOSFET gate charge)RGATE = 1.5 Ω (MOSFET gate input resistance)()[] 21LOADN2(ON)N1(ON)N1,N2(CL)IRDRDP××−+×== (0.15 × 0.0054 + 0.85 × 0.0054) × (15 A)2= 1.215 WThe power loss dissipated through the ESR of the outputcapacitor isPCOUT = (IRMS)2 × ESR = (1.5 A)2 × 1.4 mΩ = 3.15 mW2)()(×××=FLOADSWLOSSBODYLOSSBODYVIttP= 20 ns × 300 × 103 × 15 A × 0.84 × 2= 151.2 mWFeedback Resistor Network SetupIt is recommended to use RB = 15 kΩ. Calculate RT as follows:kΩ30V6.0V)6.0V8.1(kΩ15=−×=TRPSW(LOSS) = fSW × RGATE × CTOTAL × ILOAD × VIN × 2= 300 × 103 × 1.5 Ω × 3.3 × 10−9 × 15 A × 12 × 2= 534.6 mWCompensation NetworkTo calculate RCOMP, CCOMP, and CPAR, the transconductanceparameter and the current-sense gain variable are required. Thetransconductance parameter (GM) is 500 μA/V, and the current-sense loop gain is()[]()[]))002.00.5103.310300(0.5())002.062.4103.310300(62.4(9393)(+×××××++×××××=+×++×=−−BIASREGlowerFETSWREGBIASDRupperFETSWDRLOSSDRIVCfVIVCfVP= 57.12 mWA/V33.8005.02411=×==ONCSCSRAGmW6.55)002.05103.310300()V5V13()()(93)(=+×××××−=+×××−=−BIASREGtotalSWREGINLDODISSIVCfVVPwhere ACS and RON are taken from setting up the current limit(see the Programming Resistor (RES) Detect Circuit and ValleyCurrent-Limit Setting sections).The crossover frequency is 1/12th of the switching frequency:PCOUT = (IRMS)2 × ESR = (1.5 A)2 × 1.4 mΩ = 3.15 mW300 kHz/12 = 25 kHz2)(LOADLOSSDCRIDCRP×== 0.003 × (15 A)2 = 675 mWThe zero frequency is 1/4th of the crossover frequency:PCIN = (IRMS)2 × ESR = (7.5 A)2 × 1 mΩ = 56.25 mW25 kHz/4 = 6.25 kHzPLOSS = PN1,N2 + PBODY(LOSS) + PSW + PDCR + PDR + PDISS(LDO)+ PCOUT + PCIN= 1.215 W + 151.2 mW + 534.6 mW + 57.12 mW + 55.6+ 3.15 mW + 675 mW + 56.25 mW= 2.655 W6.08.13.8105001011.11025141.321025.6102510252633333××××××××××+××=×π×+=−−REFOUTCSMOUTCROSSZEROCROSSCROSSCOMPVVGGCffffR= 100 kΩ

## Similar Part No. - ADP1871

 Manufacturer Part # Datasheet Description Cirrus Logic ADP1870-0.3-EVALZ 1Mb / 10P Evaluation Kit Rev A Analog Devices ADP1872 67Kb / 1P Synchronous Current-Mode with Constant On-time, PWM Buck Rev. PrA Cirrus Logic ADP1873-0.3-EVALZ 1Mb / 10P Evaluation Kit Rev A Analog Devices ADP1874 2Mb / 44P Synchronous Buck Controller with Constant On-Time and Valley Current Mode REV. 0 ADP1874-0.3-EVALZ 2Mb / 44P Synchronous Buck Controller with Constant On-Time and Valley Current Mode REV. 0
More results

 Manufacturer Part # Datasheet Description Analog Devices ADP1874 2Mb / 44P Synchronous Buck Controller with Constant On-Time and Valley Current Mode REV. 0 ADP1882 1Mb / 40P Synchronous Current-Mode with Constant On-Time,PWM Buck Controller REV. 0 ADP1872 67Kb / 1P Synchronous Current-Mode with Constant On-time, PWM Buck Rev. PrA Vishay Siliconix SIP12117 965Kb / 17P 3 A Current Mode Constant On-Time Synchronous Buck Regulator 01-Jan-2022 SIP12116 978Kb / 17P 3 A Current Mode Constant On-Time Synchronous Buck Regulator 01-Jan-2022 SIP12116 942Kb / 18P 3 A Current Mode Constant On-Time Synchronous Buck Regulator Rev. C, 06-Mar-17 SIP12117 926Kb / 18P 3 A Current Mode Constant On-Time Synchronous Buck Regulator Rev. B, 06-Mar-17 Micrel Semiconductor MIC2124 680Kb / 24P Constant Frequency, Synchronous Current Mode Buck Controller Vishay Siliconix SIP12107 715Kb / 19P 5 V, 3 A Current-Mode Constant On-Time Synchronous Buck Regulator Rev. B, 20-Feb-12 SIP12107 911Kb / 20P 5 V, 3 A Current-Mode Constant On-Time Synchronous Buck Regulator 01-Jan-2022
More results