National Semiconductor | High-performance Analog

 

 LM3940   
1A Low Dropout Regulator for 5V to 3.3V Conversion 		Click link to Download

Features

  • Output voltage specified over temperature
  • Excellent load regulation
  • Guaranteed 1A output current
  • Requires only one external component
  • Built-in protection against excess temperature
  • Short circuit protected

    • Description

    The LM3940 is a 1A low dropout regulator designed to provide 3.3V from a 5V supply.

    The LM3940 is ideally suited for systems which contain both 5V and 3.3V logic, with prime power provided from a 5V bus.

    Because the LM3940 is a true low dropout regulator, it can hold its 3.3V output in regulation with input voltages as low as 4.5V.

    The T0-220 package of the LM3940 means that in most applications the full 1A of load current can be delivered without using an additional heatsink.

    The surface mount TO-263 package uses minimum board space, and gives excellent power dissipation capability when soldered to a copper plane on the PC board.


    Applications

  • Laptop/Desktop Computers
  • Logic Systems

    • Also Recommended
    LM2677Higher Efficiency & Better Transient Response
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    LP38690▲Lower Supplu Current , Stable With Ceramic Capacitor
    LP38692▲Lower Quiescent Current, Stable With Ceramic Output Capacitors & Enable Pin
    LP3872▲Improved Output Current, Fast Response, Lower Supply Current



    Typical Application
    click for larger image


    		Connection Diagram
    click for larger image



    Typical Performance
    click for larger image


    Parameters / ValuesLM3940 LP38690 LP38692 LP3872
    Output Current1000 mA 1000 mA 1000 mA 1500 mA
    Output Min3.3 Volt 1.8, 5.0, 2.5, 3.3 Volt 1.8, 2.5, 3.3, 5 Volt 1.8, 2.5, 3.3, 5 Volt
    Input Max Voltage7.5 Volt 10 Volt 10 Volt 7 Volt
    Dropout Voltage0.31 Volt 0.45, 0.95, 0.8, 0.65 Volt 0.45, 0.95, 0.8, 0.65 Volt 0.38 Volt
    Adjustable OutputNo No No No
    Quiescent Current0.11 mA 0.055 mA 0.055 mA 6 mA
    On/Off PinNo No Yes Yes
    PowerGood / Error FlagNo No No Yes
    RegTypeLDO LDO LDO LDO
    Temperature Min-40 deg C -40 deg C -40 deg C -40 deg C
    Temperature Max125 deg C 125 deg C 125 deg C 125 deg C
    Output Voltage3.3 Volt 1.8, 5.0, 2.5, 3.3 Volt 1.8, 2.5, 3.3, 5 Volt 1.8, 2.5, 3.3, 5 Volt
    Output Max3.3 Volt 1.8, 5.0, 2.5, 3.3 Volt 1.8, 2.5, 3.3, 5 Volt 1.8, 2.5, 3.3, 5 Volt

    Datasheets
    TitleSizeDateOther
    Language
    LM3940 1A Low Dropout Regulator for 5V to 3.3V Conversion328
    Kbytes    		19-Jul-07日本語  


    Application Notes
    TitleSizeDateOther
    Language
    AN-1061: Application Note 1061 Power Conversion in Line-Powered Equipment162
    Kbytes    		1-Oct-02日本語

    Part Number(s)
    (NSID)    		Top ViewAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3940IMP-3.3/NOPB

    LM3940IMP-3.3

    RoHS Status

    SOT-223    		Full production
    Lead Time: 16 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide1700
    AVNET-EMWorldwide17000
    DIGI-KEYWorldwide5624
    MOUSERWorldwide1133
    NEWARKAmericas1760
    RS COMPONENTSWorldwide347
    RSL MICROAsia Pacific1000
    TAYLORAmericas18325
    		$0.55 each at 1K+ pcsreel
    of
    1000
    LM3940IMPX-3.3/NOPB

    LM3940IMPX-3.3

    RoHS Status

    SOT-223    		Full production
    Lead Time: 12 weeks

     
    DistributorRegionQty
    ARROWWorldwide2000
    AVNET-EMWorldwide9925
    DIGI-KEYWorldwide0
    MOUSERWorldwide1330
    TAYLORAmericas2000
    TECHMOSAAsia Pacific4000
    		$0.55 each at 1K+ pcsreel
    of
    2000
    LM3940IS-3.3/NOPB

    LM3940IS-3.3

    RoHS Status

    TO-263    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide646
    AVNET-EMWorldwide2021
    DIGI-KEYWorldwide209
    MOUSERWorldwide265
    NEWARKAmericas404
    RS COMPONENTSWorldwide319
    TAYLORAmericas1720
    		$0.72 each at 1K+ pcsrail
    of
    45
    LM3940ISX-3.3/NOPB

    LM3940ISX-3.3

    RoHS Status

    TO-263    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    ARROWWorldwide1000
    AVNET-EMWorldwide1000
    DIGI-KEYWorldwide2000
    MOUSERWorldwide559
    NEWARKAmericas1017
    TAYLORAmericas15776
    		$0.72 each at 1K+ pcsreel
    of
    500
    LM3940IT-3.3/NOPB

    LM3940IT-3.3

    RoHS Status

    TO-220    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide349
    AVNET-EMWorldwide2584
    DIGI-KEYWorldwide5131
    MOUSERWorldwide400
    NEWARKAmericas152
    RS COMPONENTSWorldwide348
    TAYLORAmericas579
    		$0.70 each at 1K+ pcsrail
    of
    45

    Obsolete Versions
    Obsolete PartAlternate Part or SupplierSourceLast Time Buy Date
    LM3940J-3.3-MPR
    		NONE
    		NONE
    		01 Dec 2004
    LM3940J-3.3-QML
    		NONE
    		NONE
    		02 Jun 2004
    LM3940J-3.3-SCD
    		NONE
    		NONE
    		01 Dec 2004
    LM3940LD-3.3
    		NONE
    		NATIONAL SEMICONDUCTOR
    		01 Dec 2009
    LM3940LDX-3.3
    		NONE
    		NATIONAL SEMICONDUCTOR
    		01 Dec 2009
    LM3940WG3.3-MPR
    		NONE
    		NONE
    		01 Dec 2004
    LM3940WG3.3-QML
    		NONE
    		NONE
    		02 Jun 2004
    LM3940WG3.3-SCD
    		NONE
    		NONE
    		01 Dec 2004

    All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

    Moisture Sensitivity Level Data for LM3940.

    A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

    National's certificate of product compliance for LM3940 is located at RoHS Status.

    Part Number(s)
    (NSID)    		Weight
    (milligrams)    		TypePinsMSL RatingPeak ReflowRoHS
    Status    		CAD SymbolsModelsPackage
    Marking
    Format
    LM3940IMP-3.3/NOPB

    LM3940IMP-3.3
    		120.612
    121.002
    		SOT-22341
    1    		260
    260    		DetailDownloadN/A
    		XYTT
    L52B
    LM3940IMPX-3.3/NOPB

    LM3940IMPX-3.3
    		120.612
    121.002
    		SOT-22341
    1    		260
    260    		DetailDownloadN/A
    		XYTT
    L52B
    LM3940IS-3.3/NOPB

    LM3940IS-3.3
    		1289.225
    1289.976
    		TO-26333
    3    		245
    235    		DetailDownloadN/A
    		NSUZXYTTE#
    LM3940IS
    -3.3 P+
    LM3940ISX-3.3/NOPB

    LM3940ISX-3.3
    		1289.225
    1289.976
    		TO-26333
    3    		245
    235    		DetailDownloadN/A
    		NSUZXYTTE#
    LM3940IS
    -3.3 P+
    LM3940IT-3.3/NOPB

    LM3940IT-3.3
    		1991.806
    1993.446
    		TO-22031
    1    		NA
    NA    		DetailDownloadN/A
    		NSUZXYTTE#
    LM3940IT
    -3.3 P+

    All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

    Moisture Sensitivity Level Data for LM3940.

    A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

    National's certificate of product compliance for LM3940 is located at RoHS Status.

    CAD Symbols and Models
    Download LM3940 CAD Symbols
    		 Models
    N/A


    Reliability Metrics
    Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
    LM3940IMP-3.3SLM04404600353250011002356520
    LM3940IMPX-3.3SLM04404600353250011002356520
    LM3940IS-3.3SLM04404600353250011002356520
    LM3940ISX-3.3SLM04404600353250011002356520
    LM3940IT-3.3SLM04404600353250011002356520

    Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

    For more information on Reliability Metrics, please click here.


    All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

    Moisture Sensitivity Level Data for LM3940.

    A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

    National's certificate of product compliance for LM3940 is located at RoHS Status.

    Obsolete Versions
    Obsolete PartAlternate Part or SupplierSourceLast Time Buy Date
    LM3940J-3.3-MPR
    		NONE
    		NONE
    		01 Dec 2004
    LM3940J-3.3-QML
    		NONE
    		NONE
    		02 Jun 2004
    LM3940J-3.3-SCD
    		NONE
    		NONE
    		01 Dec 2004
    LM3940LD-3.3
    		NONE
    		NATIONAL SEMICONDUCTOR
    		01 Dec 2009
    LM3940LDX-3.3
    		NONE
    		NATIONAL SEMICONDUCTOR
    		01 Dec 2009
    LM3940WG3.3-MPR
    		NONE
    		NONE
    		01 Dec 2004
    LM3940WG3.3-QML
    		NONE
    		NONE
    		02 Jun 2004
    LM3940WG3.3-SCD
    		NONE
    		NONE
    		01 Dec 2004

    [Information as of 9-Feb-2012]
    Copyright © 2011 National Semiconductor Corporation