National Semiconductor | High-performance Analog

 

 LM3554   

Synchronous Boost Converter with 1.2A Dual High Side LED Driver and I2C Compatible Interface C Compatible Interface
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Features

  • Dual High Side Current Sources
  • Grounded Cathode Allowing for Better Heat Sinking and LED Routing
  • >90% Efficiency
  • Ultra-Small Solution Size: < 23mm 2
  • Four Operating Modes: Torch, Flash, LED Indicator and Voltage Output
  • Accurate and Programmable LED Current from 37.5mA to 1.2A
  • Programmable 4.5V or 5.0V Constant Output Voltage
  • Hardware Flash and Torch Enable
  • LED Thermal Sensing and Current Scaleback
  • Software Selectable Input Voltage Monitor
  • Programmable Flash Timeout
  • Dual Synchronization Inputs for RF Power Amplifier Pulse Events
  • Open and Short LED Detection
  • Active High Hardware Enable for Protection Against System Faults
  • 400kHz I 2C-Compatible Interface
  • 16-Bump (1.7mm × 1.7mm × 0.6mm) micro SMD
  • Description

    The LM3554 is a 2MHz fixed frequency, current mode synchronous boost converter. The device is designed to operate as a dual 600mA (1.2A total) constant-current driver for high-current white LEDs, or as a regulated 4.5V or 5V voltage source.

    The dual high-side current sources allow for grounded cathode LED operation. An adaptive regulation method ensures the current source for each LED remains in regulation and maximizes efficiency.

    The main features include: an I 2C-compatible interface for controlling the LED current or the desired output voltage, a hardware Flash enable input for direct triggering of the Flash pulse, and dual TX inputs which force the Flash pulse into a low-current Torch mode allowing for synchronization to RF power amplifier events or other high-current conditions. Additionally, an active high hardware enable (HWEN) input provides a hardware shutdown during system software failures.

    Five protection features are available within the LM3554 including a software selectable input voltage monitor, an internal comparator for interfacing with an external temperature sensor, four selectable current limits to ensure the battery current is kept below a predetermined peak level, an over-voltage protection feature to limit the output voltage during LED open circuits, and an output short circuit protection which limits the output current during shorts to GND. Additionally, the device provides various fault indicators including: a thermal fault flag indicating the LED temperature has tripped the thermal threshold, a flag indicating a TX event has occurred, a flag indicating the flash timeout counter has expired, a flag indicating the devices die temperature has reached the thermal shutdown threshold, and a flag indicating an open or short LED.


    Applications

  • Camera Phone LED Flash Controller
  • Class D Audio Amplifier Power
  • LED Current Source Biasing


  • Typical application circuit

     

    ParametersValues
    Regulated LEDs 2
    Total LED Current 1200 mA
    Boost Type Inductive
    Switching Frequency 2000 kHz
    Efficiency (peak) 95 %
    Input Min Voltage 2.7 Volt
    Input Max Voltage 5.5 Volt
    LED Configuration Parallel
    Current Matching 0.5%
    OutputMax Voltage 5.4 Volt
    Supply Current 2.7 mA
    Switching Type Fixed Freq
    Special Features Indicator, LED Temp Sense, VOUT Mode, I2C Compatible Interface, Dual TX Interrupt, VIN Monitor, Fault Detection, Programmable Current Limit
    PWM BrightCtrl No
    Analog-V BrightCtrl No
    Ambient Light Compensation No
    RGB-LED No
    Temperature Min -30 deg C
    Temperature Max 85 deg C
    RegType Switching Regulator
    PowerWise No

    Datasheets
    TitleSizeDateOther
    Language
    LM3554 Synchronous Boost Converter with 1.2A Dual High Side LED Driver and I2C Compatible Interface C Compatible Interface2891
    Kbytes
    12-Apr-11   


    Other Technical Documents
    TitleTypeDate
    High-Performance LED Flash for Camera PhonesExternal Article 2009-08-10
    Things to Keep in Mind When Designing Power Management CircuitryExternal Article 2009-10-20

    Part Number(s)
    (NSID)
    Top ViewAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3554TME/NOPB


    RoHS Status


    MICRO SMD
    Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    AVNET-EMWorldwide134
    DIGI-KEYWorldwide1095
    FARNELLEurope and Asia126
    NEWARKAmericas126
    $1.30 each at 1K+ pcsreel
    of
    250
    LM3554TMX/NOPB


    RoHS Status


    MICRO SMD
    Full production
    Lead Time: 10 weeks

     
    DistributorRegionQty
    CEACAsia Pacific30000
    DIGI-KEYWorldwide0
    $1.30 each at 1K+ pcsreel
    of
    3000

    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 LM3554.

    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 LM3554 is located at RoHS Status.

    Part Number(s)
    (NSID)
    DescriptionAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3554TMEEV/NOPB

    LM3554TMEEV Evaluation BoardFull production
    Lead Free (RoHS)

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    $150.00 each1
    Not for sale on web, sales force only.



    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
    LM3554TME/NOPB

    3.689
    MICRO SMD161260DetailN/AN/A
    XYTT
    I SF
    LM3554TMX/NOPB

    3.689
    MICRO SMD161260DetailN/AN/A
    XYTT
    I SF

    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 LM3554.

    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 LM3554 is located at RoHS Status.

    CAD Symbols and Models
    N/A
     Models
    N/A


    Reliability Metrics
    Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
    LM3554TMECMOS70213010015840003449464325
    LM3554TMXCMOS70213010015840003449464325

    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 LM3554.

    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 LM3554 is located at RoHS Status.

    [Information as of 3-Feb-2012]