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LT3070

3070fa

pin Functions

MARGSEL (Pin 21):MarginingEnableandPolaritySelec-

tion.Thisthree-statepindeterminesboththepolarityand

theactivestateofthemarginingfunction.Thelogic

low

thresholdislessthan250mVreferencedtoGNDanden-

ablesnegativevoltagemargining.Thelogic

highthreshold

isgreaterthanVBIAS–250mVandenablespositivevoltage

margining.Thevoltagerangebetweenthesetwologic

thresholdsassetbyawindowcomparatordefinesthe

logic

Hi-Zstateanddisablesthemarginingfunction.

MARGTOL (Pin 22): Margining Tolerance. This three-

statepinselectstheabsolutevalueofmargining(1%,

3%or5%)ifenabledbytheMARGSELinput.Thelogic

lowthresholdislessthan250mVreferencedtoGNDand

enableseither±1%changeinVOUTdependingonthestate

oftheMARGSELpin.Thelogichighthresholdisgreater

thanVBIAS–250mVandenableseither±5%changein

VOUTdependingonthestateoftheMARGSELpin.The

voltagerangebetweenthesetwologicthresholdsasset

byawindowcomparatordefinesthelogic

Hi-Zstateand

enableseither±3%changeinVOUTdependingonthestate

oftheMARGSELpin.

VO0, VO1 and VO2 (Pins 23, 24, 25):OutputVoltageSe-

lect.Thesethree-statepinscombinetoselectanominal

outputvoltagefrom0.8Vto1.8Vinincrementsof50mV.

Outputvoltageislimitedto1.8Vmaximumbyaninternal

override of VO1whenVO2=high.Theinputlogiclow

thresholdislessthan250mVreferencedtoGNDandthe

logic

highthresholdisgreaterthanVBIAS–250mV.The

rangebetweenthesetwothresholdsassetbyawindow

comparatordefinesthelogic

Hi-Zstate.SeeTable1inthe

ApplicationsInformationsectionthatdefinestheVO2,VO1

andVO0settingsversusVOUT.

BIAS (Pin 27):BiasSupply.Thispinsuppliescurrentto

theinternalcontrolcircuitryandtheoutputstagedriving

thepasstransistor.TheLT3070requiresaminimum2.2µF

bypasscapacitorforstabilityandproperoperation.To

ensureproperoperation,theBIASvoltagemustsatisfy

thefollowingconditions:2.2V≤VBIAS≤3.6VandVBIAS≥

(1.25•VOUT+1V).ForVOUT≤0.95V,theminimumBIAS

voltageislimitedto2.2V.

EN (Pin 28):Enable.Thispinenables/disablestheoutput

deviceonly.Theinternalreferenceandallsupportfunctions

areactiveifVBIASisaboveitsUVLOthreshold.Pulling

ENlowkeepsthereferencecircuitactive,butdisables

theoutputpasstransistorandputstheLT3070intoalow

power

napmode.DrivetheENpinwitheitheradigitallogic

portoranopen-collectorNPNoranopen-drainNMOS

terminatedwithapull-upresistortoVBIAS.Thepull-up

resistormustbelessthan35ktomeettheVIHcondition

oftheENpin.Ifunused,connectENtoBIAS.

BIAS

LT3070

VO2

VO1

VBIAS

VIN

VO0

MARGSEL

MARGTOL

VIOC

SENSE

OUT

PWRGD

REF/BYP

GND

3070 F01

LOAD

Figure 1. Kelvin Sense Connection

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