Datasheet

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0.015x16
0.120
0.0256
0.230
0.040
0.134
0.197
0.040
0.050
0.050
0.013DIA
8PL
Minimumrecommendedexposedcopper
areaforPowerPAD.Somestencilsmay
require10percentlargerarea.
ConnectPin10 AGNDandPin11PGND
to AnalogGroundplaneinthisareafor
optimumperformance.
Minimumrecommendedtop
side AnalogGroundarea.
Minimumrecommendedthermalvias:4x0.013dia.Inside
exposedPowerPADareaand4x0.013dia.Underdeviceas
shown. Additionalviasmaybeusediftopsidegroundareaisextended.
0.080
MODELFORLOOPRESPONSE
TPS54550
SLVS623A–MARCH2006–REVISEDAPRIL2006
Figure27.ThermalConsiderationsforPowerPADLayout
Thefeedforwardgainismodeledasanideal
voltage-controlledvoltagesourcewithagainof8
V/V.The1-mVacvoltagebetweennodesaandb
Figure28showsanequivalentmodelforthe
effectivelybreaksthecontrolloopforthefrequency
TPS54550controlloopwhichcanbemodeledina
responsemeasurements.Plottingb/cshowsthe
circuitsimulationprogramtocheckfrequency
small-signalresponseofthepowerstage.Plotting
responseanddynamicloadresponse.Theerror
c/ashowsthesmall-signalresponseofthefrequency
amplifierintheTPS54550isavoltageamplifierwith
compensation.Plottinga/bshowsthesmall-signal
80dB(10000V/V)ofopen-loopgain.Theerror
responseoftheoverallloop.Thedynamicload
amplifiercanbemodeledusinganideal
responsecanbecheckedbyreplacingtheR
L
witha
voltage-controlledcurrentsourceasshownin
currentsourcewiththeappropriateloadstep
Figure28witharesistorandcapacitorontheoutput.
amplitudeandsteprateinatimedomainanalysis.
TheTPS54550devicehasanintegratedfeed
forwardcompensationcircuitwhicheliminatesthe
impactoftheinputvoltagechangestotheoverall
looptransferfunction.
17
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