TheTPS61180/1/2ICsprovidehighlyintegratedsolutionsformediasizeLCDbacklight.Thesedeviceshaveabuilt-inhighefficiencyboostregulatorwithintegrated1.5A/40VpowerMOSFET.Thesixcurrentsinkregulatorsprovidehighprecisioncurrentregulationandmatching.Intotal,thedevicecansupportupto60WLED.Inaddition,theboostoutputautomaticallyadjustsitsvoltagetotheWLEDforwardvoltagetoimproveefficiency.
Thedevicessupportpulsewidthmodulation(PWM)brightnessdimming.Duringdimming,theWLEDcurrentisturnedon/offatthedutycycleandfrequencydeterminedbythePWMsignalinputontheDCRTLpin.OnepotentialissueofPWMdimmingisaudiblenoisesfromtheoutputceramiccapacitors.TheTPS61180/1/2familyisdesignedtominimizethisoutputACrippleacrossawidedimmingdutycycleandfrequencyrange;and,thereforereducetheaudiblenoise.
TheTPS61180/1/2ICsprovideadriveroutputforanexternalPFETconnectedbetweentheinputandinductor.Duringshortcircuitorover-currentconditions,theICsturnofftheexternalPFETanddisconnectthebatteryfromtheWLEDs.ThePFETisalsoturnedoffduringICshutdown(trueshutdown)topreventanyleakagecurrentofthebattery.Thedevicealsointegratesover-voltageprotection,soft-startandthermalshutdown.
TheTPS61180ICrequiresexternal3.3VICsupply,whileTPS61181andTPS61182ICshaveabuilt-inlinearregulatorfortheICsupply.Allthedevicesareina3×3mmQFNpackage.
TPS6118x主要特性:
5Vto24VInputVoltage
Integrated1.5A40VMOSFET
1.0MHz/1.3MHzSwitchingFrequency
BoostOutputAuto-AdaptivetoWLEDVoltages
SmallExternalComponents
IntegratedLoopCompensation
SixCurrentSinkof25mA
Upto10WLEDinSeries
LessThan3%CurrentMatchingandAccuracy
100:1PWMBrightnessDimmingRange
MinimizedOutputRippleUnderPWMDimming
DriverforInput/OutputIsolationPFET
TrueShutdown
OverVoltageProtection
WLEDOpen/ShortProtection
Built-inSoftStart
16L3mm×3mmQFN
TPS6118x应用:
NotebookLCDDisplayBacklight
UMPCLCDDisplayBacklight
BacklightforMediaFormFactorLCDdisplay
图1.TPS6118x功能方框图
图2.TPS61181/1典型应用电路图
图3.TPS6118x评估板电路图
表1.TPS6118x评估板元件清单(BOM)
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