Texas Instruments LM2991 Handleiding

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LM2991

GND

ADJ

+

C

OUT

R1

R2

Unregulated

Input

ON/OFF

C

IN

+

OUT

IN

Regulated

Input

**

*

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AnIMPORTANTNOTICEattheendofthisdatasheetaddressesavailability,warranty,changes,useinsafety-criticalapplications,

intellectualpropertymattersandotherimportantdisclaimers.PRODUCTIONDATA.

LM2991

SNVS099I–MAY1999–REVISEDOCTOBER2016

LM2991NegativeLow-DropoutAdjustableRegulator

1

1Features

1

•OutputVoltageAdjustablefrom−3Vto−24V,

Typically−2Vto−25V

•OutputCurrentinExcessof1A

•DropoutVoltageTypically0.6Vat1-ALoad

•LowQuiescentCurrent

•InternalShortCircuitCurrentLimit

•InternalThermalShutdownWithHysteresis

•TTL,CMOSCompatibleON/OFFSwitch

•FunctionalComplementtotheLM2941Series

2Applications

•PostSwitcherRegulator

•Local,On-Card,Regulation

•BatteryOperatedEquipment

•Industrial

•Instrumentation

3Description

TheLM2991isalowdropoutadjustablenegative

regulatorwithaoutputvoltagerangebetween−3Vto

−24V.TheLM2991providesupto1Aofload

currentandfeaturesaON/OFFpinforremote

shutdowncapability.

TheLM2991usesnewcircuitdesigntechniquesto

providealowdropoutvoltage,lowquiescentcurrent

andlowtemperaturecoefficientprecisionreference.

Thedropoutvoltageat1-Aloadcurrentistypically

0.6Vandanensuredworst-casemaximumof1V

overtheentireoperatingtemperaturerange.The

quiescentcurrentistypically1mAwitha1-Aload

currentandaninput-outputvoltagedifferentialgreater

than3V.Auniquecircuitdesignoftheinternalbias

supplylimitsthequiescentcurrenttoonly9mA

(typical)whentheregulatorisinthedropoutmode

(V

OUT

−V

IN

≤3V).

TheLM2991isshort-circuitproof,andthermal

shutdownincludeshysteresistoenhancethe

reliabilityofthedevicewheninadvertentlyoverloaded

forextendedperiods.TheLM2991isavailablein5-

leadTO-220andDDPAK/TO-263packagesandis

ratedforoperationovertheautomotivetemperature

rangeof−40°Cto+125°C.Mil-Aeroversionsarealso

available.

DeviceInformation

(1)

PARTNUMBERPACKAGEBODYSIZE(NOM)

LM2991

DDPAK/TO-263(5)10.20mm×9.00mm

TO-220(5)14.99mm×10.16mm

(1)Forallavailablepackages,seetheorderableaddendumat

theendofthedatasheet.

TypicalApplication

V

OUT

=V

REF

(1+R2/R1)

*Requirediftheregulatorislocatedfurtherthan6inchesfromthepowersupplyfiltercapacitors.A1-μFsolid

tantalumora10-μFaluminumelectrolyticcapacitorisrecommended.

**Requiredforstability.Mustbeatleasta10-μFaluminumelectrolyticora1-μFsolidtantalumtomaintainstability.

Maybeincreasedwithoutboundtomaintainregulationduringtransients.Locatethecapacitorascloseaspossibleto

theregulator.Theequivalentseriesresistance(ESR)iscritical,andshouldbelessthan10Ωoverthesameoperating

temperaturerangeastheregulator.

Product specificaties