National Semiconductor | High-performance Analog

 

 LM5642X   
High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization from the PowerWise® Family		 Click link to Download

Features

  • Two synchronous buck regulators
  • 180° out of phase operation
  • 200 kHz fixed nominal frequency: LM5642
  • 375 kHz fixed nominal frequency: LM5642X
  • Synchronizable switching frequency from 150 kHz to 250 kHz for the LM5642 and 200 kHz to 500 kHz for the LM5642X
  • 4.5V to 36V input range
  • 50 µA Shutdown current
  • Adjustable output from 1.3V to 90% of Vin
  • 0.04% (typical) line and load regulation accuracy
  • Current mode control with or without a sense resistor
  • Independent enable/soft-start pins allow simple sequential startup configuration.
  • Configurable for single output parallel operation. (See )
  • Adjustable cycle-by-cycle current limit
  • Input under-voltage lockout
  • Output over-voltage latch protection
  • Output under-voltage protection with delay
  • Thermal shutdown
  • Self discharge of output capacitors when the regulator is OFF
  • TSSOP and eTSSOP (Exposed PAD) packages

    • Description

    The LM5642 series consists of two current mode synchronous buck regulator controllers operating 180° out of phase with each other at a normal switching frequency of 200kHz for the LM5642 and at 375kHz for the LM5642X.

    Out of phase operation reduces the input RMS ripple current, thereby significantly reducing the required input capacitance. The switching frequency can be synchronized to an external clock between 150 kHz and 250 kHz for the LM5642 and between 200 kHz and 500 kHz for the LM5642X. The two switching regulator outputs can also be paralleled to operate as a dual-phase, single output regulator.

    The output of each channel can be independently adjusted from 1.3V to 90% of Vin. An internal 5V rail is also available externally for driving bootstrap circuitry.

    Current-mode feedback control assures excellent line and load regulation and wide loop bandwidth for excellent response to fast load transients. Current is sensed across either the Vds of the top FET or across an external current-sense resistor connected in series with the drain of the top FET.

    The LM5642 features analog soft-start circuitry that is independent of the output load and output capacitance making the soft-start behavior more predictable and controllable than traditional soft-start circuits.

    Over-voltage protection is available for both outputs. A UV-Delay pin is also available to allow delayed shut off time for the IC during an output under-voltage event.


    Applications

  • Embedded Computer Systems
  • Navigation Systems
  • Telecom Systems
  • Set-Top Boxes
  • WebPAD
  • Point Of Load Power Architectures

    • Also Recommended
    LM2642▲Pin Compatible Except That SYNC Is Replaced By PGOOD, And Has Fixed 300 KHz OSC
    LM2647Dual Synchronous Buck Controller With Output Voltages As Low As 0.6V
    LM5642▲150-200 KHz Osc Switch Frequencies
    LM2633▲Dual Synchronous Buck + LDO Controller. Perfect For FPGAs And Similar Devices
    LM2648▲Triple / Quad Channel Synchronous Buck Controller



    Parameters / ValuesLM5642X LM2642 LM5642 LM2633 LM2648
    Output Current20000 mA 20000 mA 20000 mA
    Input Min Voltage4.5 Volt 4.5 Volt 4.5 Volt
    Input Max Voltage36 Volt 30 Volt 36 Volt
    Feedback Voltage1.2364 Volt 1.238 Volt 1.2364 Volt
    Feedback Tolerance1.5 % 2 % 1.5 %
    Frequency Min200 kHz 300 kHz 150 kHz
    Frequency Max500 kHz 300 kHz 250 kHz
    Efficiency (peak)90 % Undefined % 90 %
    Output Range1.3V to 96% of Vin 1.238V-27V (each output) 1.3V to 96% of Vin
    Adj Switch FrequencyYes No Yes
    Adjustable OutputYes Yes Yes
    Synchronous RectificationYes Yes Yes
    On/Off PinYes Yes Yes
    PowerGood / Error FlagNo Yes No
    SoftStartYes Yes Yes
    Sync PinYes No Yes
    InvertingNo No No
    FlybackNo No No
    Lossless Current SenseYes Yes Yes
    RegTypeSwitching Controller Switching Controller Switching Controller
    Temperature Min-40 deg C -40 deg C -40 deg C
    Temperature Max125 deg C 125 deg C 125 deg C
    Channels2 Channels 2 Channels 2 Channels
    Special Features180deg out-of-phase channels; individual soft-start allows sequencing 180deg out-of-phase channels; Individual softstart allows sequencing 180deg out-of-phase channels; individual soft-start allows sequencing
    TopologyBuck Buck Buck
    PWM ModeCurrent Current Current
    Step-DownYes Yes Yes
    Step-UpNo No No
    Output PowerUndefined Watt Undefined Watt Undefined Watt
    Output Min1.3 Volt 1.238 Volt 1.3 Volt
    AutomotiveYes
    PowerWiseYes Yes

    Datasheets
    TitleSizeDateOther
    Language
    LM5642X High Voltage, Dual Synchronous Buck Converter with Oscillator Synchronization824
    Kbytes    		18-May-11   


    Other Technical Documents
    TitleTypeDate
    PCPM | Peak Current-Mode DC-DC Converter Stability AnalysisExternal Article 2010-06-01

    Part Number(s)
    (NSID)    		Top ViewAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM5642XMH/NOPB

    LM5642XMH

    RoHS Status

    TSSOP EXP PAD    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide49
    AVNET-EMWorldwide177
    DIGI-KEYWorldwide250
    MOUSERWorldwide177
    TAYLORAmericas49
    		$1.90 each at 1K+ pcsrail
    of
    48
    LM5642XMHX/NOPB

    LM5642XMHX

    RoHS Status

    TSSOP EXP PAD    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$1.90 each at 1K+ pcsreel
    of
    2500
    LM5642XMT/NOPB

    LM5642XMT

    RoHS Status

    TSSOP    		Full production
    Lead Time: 8 weeks

    Samples
    DistributorRegionQty
    ARROWWorldwide1731
    AVNET-EMWorldwide191
    DIGI-KEYWorldwide192
    FARNELLEurope and Asia249
    MOUSERWorldwide192
    NEWARKAmericas12
    RSL MICROAsia Pacific192
    TAYLORAmericas1731
    		$1.90 each at 1K+ pcsrail
    of
    48
    LM5642XMTX/NOPB

    LM5642XMTX

    RoHS Status

    TSSOP    		Full production
    Lead Time: 8 weeks

     
    DistributorRegionQty
    AECO TECHAsia Pacific1000
    ARROWWorldwide2500
    DIGI-KEYWorldwide0
    RSL MICROAsia Pacific5000
    TAYLORAmericas2500
    		$1.90 each at 1K+ pcsreel
    of
    2500

    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 LM5642X.

    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 LM5642X is located at RoHS Status.

    Part Number(s)
    (NSID)    		Weight
    (milligrams)    		TypePinsMSL RatingPeak ReflowRoHS
    Status    		CAD SymbolsModelsPackage
    Marking
    Format
    LM5642XMH/NOPB

    LM5642XMH
    		117.59
    118.211
    		TSSOP EXP PAD281
    1    		260
    260    		DetailDownloadN/A
    		NSUZXYTTE#
    LM5642
    XMH
    LM5642XMHX/NOPB

    LM5642XMHX
    		117.59
    118.211
    		TSSOP EXP PAD281
    1    		260
    260    		DetailDownloadN/A
    		NSUZXYTTE#
    LM5642
    XMH
    LM5642XMT/NOPB

    LM5642XMT
    		111.551
    112.001
    		TSSOP283
    3    		260
    235    		DetailDownloadN/A
    		NSUZXYTTE#
    LM5642
    XMT
    LM5642XMTX/NOPB

    LM5642XMTX
    		111.551
    112.001
    		TSSOP283
    3    		260
    235    		DetailDownloadN/A
    		NSUZXYTTE#
    LM5642
    XMT

    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 LM5642X.

    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 LM5642X is located at RoHS Status.

    CAD Symbols and Models
    Download LM5642X CAD Symbols
    		 Models
    N/A


    Reliability Metrics
    Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
    LM5642XMHABCD15004268000639400011814314958
    LM5642XMHXABCD15004268000639400011814314958
    LM5642XMTABCD15004268000639400011814314958
    LM5642XMTXABCD15004268000639400011814314958

    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 LM5642X.

    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 LM5642X is located at RoHS Status.

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