National Semiconductor | High-performance Analog

 

 LM1771   
Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation from the PowerWise® Family		 Click link to Download

Features
  • Input voltage range of 2.8V to 5.5V
  • 0.8V reference voltage
  • Precision enable
  • No compensation required
  • Constant frequency across input range
  • Low quiescent current of 400 µA
  • Internal soft-start
  • Short circuit protection
  • Tiny LLP-6 package and MSOP-8 package

    • Description

    The LM1771 is an efficient synchronous buck switching controller with a precision enable requiring no external compensation. The constant on-time control scheme provides a simple design free of compensation components, allowing minimal component count and board space. The precision enable pin allows flexibility in sequencing multiple rails and setting UVLO. The LM1771 also incorporates a unique input feed-forward to maintain a constant frequency independent of the input voltage. The LM1771 is optimized for a low voltage input range of 2.8V to 5.5V and can provide an adjustable output as low as 0.8V. Driving an external high side PFET and low side NFET it can provide efficiencies as high as 95%.

    Three versions of the LM1771 are available depending on the switching frequency desired for the application. Nominal switching frequencies are in the range of 100kHz to 1000kHz.


    Applications

  • Simple To Design, High Efficiency Step Down Switching Regulators
  • FPGAs, DSPs, and ASIC Power Supplies
  • Set-Top Boxes
  • Cable Modems
  • Printers
  • Digital Video Recorders
  • Servers
  • Graphic Cards

    • Also Recommended
    LM1770▲SOT23 Package
    LM2853▲3A Integrated FETs PWM Version



    Typical Application
    *click for larger image


    		Block Diagram
    *click for larger image



    Typical Performance
    *click for larger image


    Parameters / ValuesLM1771 LM1770 LM2853
    Output Current6000 mA 4000 mA 3000 mA
    Input Min Voltage2.8 Volt 2.8 Volt 3 Volt
    Input Max Voltage5.5 Volt 5.5 Volt 5.5 Volt
    Feedback Voltage0.8 Volt 0.8 Volt Undefined Volt
    Feedback Tolerance2 % 2 %
    Frequency Min300 kHz 300 kHz 550 kHz
    Frequency Max1000 kHz 1000 kHz 550 kHz
    Efficiency (peak)95 % 95 % 95 %
    Output Range0.8V to 4.5V 0.8V to 4.5V 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5
    Adj Switch FrequencyNo No No
    Adjustable OutputYes Yes No
    Synchronous RectificationYes Yes Yes
    On/Off PinYes No Yes
    PowerGood / Error FlagNo No No
    SoftStartYes Yes Yes
    Sync PinNo No No
    InvertingNo Yes No
    FlybackNo No No
    Lossless Current SenseNo No
    RegTypeSwitching Controller Switching Controller Switching Regulator
    Temperature Min-40 deg C -40 deg C -40 deg C
    Temperature Max125 deg C 125 deg C 125 deg C
    Channels1 Channels 1 Channels
    Special FeaturesPrecision enable for sequencing multiple rails No compensation required Internal compensation, low standby current
    TopologyBuck Buck Synchronous Buck
    PWM ModeConstant on-time Constant on-time Voltage Mode Control
    Step-DownYes No Yes
    Step-UpNo No
    Output PowerUndefined Watt Undefined Watt
    Output Max4.5 Volt 4.5 Volt 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5 Volt
    Output Min0.8 Volt 0.8 Volt 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5 Volt
    PowerWiseYes Yes Yes
    Part Number(s)
    (NSID)    		Top ViewAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM1771SMM/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    DIGI-KEYWorldwide1913
    MOUSERWorldwide1000
    RS COMPONENTSWorldwide180
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771SMMX/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 8 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    3500
    LM1771SSD/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 8 weeks

    Samples
    DistributorRegionQty
    DIGI-KEYWorldwide0
    RS COMPONENTSWorldwide250
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771SSDX/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    4500
    LM1771TMM/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 8 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide1000
    DIGI-KEYWorldwide1981
    FARNELLEurope and Asia122
    MOUSERWorldwide1000
    RS COMPONENTSWorldwide1000
    TAYLORAmericas1000
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771TMMX/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 8 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    3500
    LM1771TSD/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    AVNET-EMWorldwide1000
    DIGI-KEYWorldwide1356
    MOUSERWorldwide1000
    RS COMPONENTSWorldwide250
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771TSDX/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    4500
    LM1771UMM/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 8 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide1000
    DIGI-KEYWorldwide1330
    FARNELLEurope and Asia1071
    MOUSERWorldwide1000
    RS COMPONENTSWorldwide995
    TAYLORAmericas1000
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771UMMX/NOPB


    RoHS Status

    MINI SOIC    		Full production
    Lead Time: 8 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    3500
    LM1771USD/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    DIGI-KEYWorldwide1616
    MOUSERWorldwide1000
    RS COMPONENTSWorldwide250
    		$0.85 each at 1K+ pcsreel
    of
    1000
    LM1771USDX/NOPB


    RoHS Status

    LLP    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.85 each at 1K+ pcsreel
    of
    4500

    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 LM1771.

    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 LM1771 is located at RoHS Status.

    Part Number(s)
    (NSID)    		DescriptionAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM1771EVAL
    		Low-Voltage Synchronous Buck Controller with Precision Enable and No External CompensationFull production


     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    MOUSERWorldwide1
    		$38.00 each1

    Description:

    LM1771 Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation

    Features:

    • Input voltage range of 2.8V to 5.5V
    • 0.8V reference voltage
    • Precision enable
    • No compensation required
    • Constant frequency across input range
    • Low quiescent current of 400 mA
    • Internal soft-start
    • Short circuit protection
    • Tiny LLP-6 package and MSOP-8 package

    Applications:

    • Simple to design, High-Efficiency Step-Down Switching Regulators
    • FPGAs, DSPs, and ASIC Power Supplies
    • Set-top Boxes
    • Cable Modems
    • Printers
    • Digital Video Recorders
    • Servers
    • Graphic Cards

    Contents:

    • A fully assembled LM1771 eval board
    • LM1771 datasheet
    • LM1771 evaluation board appnote



    National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C1) and Banned Substances and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at: www.national.com/en/packaging/greennopb.html. Lead free products are RoHS compliant.

    Lead Free product status is available through the search tool located here

    Part Number(s)
    (NSID)    		Weight
    (milligrams)    		TypePinsMSL RatingPeak ReflowRoHS
    Status    		CAD SymbolsModelsPackage
    Marking
    Format
    LM1771SMM/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNRB
    LM1771SMMX/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNRB
    LM1771SSD/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771S
    LM1771SSDX/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771S
    LM1771TMM/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNSB
    LM1771TMMX/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNSB
    LM1771TSD/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771T
    LM1771TSDX/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771T
    LM1771UMM/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNTB
    LM1771UMMX/NOPB

    		29.851
    30.002
    		MINI SOIC81260DetailDownloadN/A
    		ZXTT
    SNTB
    LM1771USD/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771U
    LM1771USDX/NOPB

    		21.032
    21.102
    		LLP61260DetailDownloadN/A
    		ZXYTT
    1771U

    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 LM1771.

    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 LM1771 is located at RoHS Status.

    CAD Symbols and Models
    Download LM1771 CAD Symbols
    		 Models
    N/A


    Reliability Metrics
    Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
    LM1771SMMCS065247473430552700011568301341
    LM1771SMMXCS065247473430552700011568301341
    LM1771SSDCS065247473430552700011568301341
    LM1771SSDXCS065247473430552700011568301341
    LM1771TMMCS065247473430552700011568301341
    LM1771TMMXCS065247473430552700011568301341
    LM1771TSDCS065247473430552700011568301341
    LM1771TSDXCS065247473430552700011568301341
    LM1771UMMCS065247473430552700011568301341
    LM1771UMMXCS065247473430552700011568301341
    LM1771USDCS065247473430552700011568301341
    LM1771USDXCS065247473430552700011568301341

    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 LM1771.

    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 LM1771 is located at RoHS Status.

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