National Semiconductor | High-performance Analog

 

 LM3687   
Step-Down DC-DC Converter with Integrated Low Dropout Regulator and Startup Mode from the PowerWise® Family		 Click link to Download

Features

DC-DC Converter:

  • 750mA maximum load capability
  • 1.8MHz PWM fixed switching frequency (typ.)
  • Automatic PFM/PWM mode switching
  • 27µA typ. Quiescent Current
  • Internal synchronous rectification for high efficiency
  • Internal soft start

    • Dual Rail Linear Regulator:

  • Startup Mode
  • Load transients < 25mVpeak typ.
  • Line transients < 1mVpeak typ.
  • Very Low Dropout Voltage: 82mV typ. at 350mA load current
  • 0.7V ≤ VIN_LIN ≤ 4.5V
  • 10µA typical IQ from VIN_LIN
  • 350mA maximum load capability

    • Combined Common Features:

  • 65µA typical Quiescent Current from VBATT if both regulators are enabled
  • 750mA maximum combined load capability in post regulation setup (DC-DC 400mA + Linear Regulator 350mA)
  • 1100mA maximum total load capability in independent mode of operation (DC-DC: 750mA, Linear Regulator: 350mA)
  • Operates from a single Li-Ion cell or 3 cell NiMH/NiCd batteries
  • Only four tiny surface-mount external components required (one inductor, three ceramic capacitors)
  • Small 9-bump micro SMD package
  • Over-temperature, current overload and under-voltage protection

    • Description

    The LM3687 is a step-down DC-DC converter with an integrated low dropout Linear Regulator optimized for powering ultra-low voltage circuits from a single Li-Ion cell or 3 cell NiMH/NiCd batteries. It provides a dual output with fixed output voltages and combined load current up to 750mA in post regulation mode or 1100mA in independent mode of operation, over an input voltage range from 2.7V to 5.5V. There are several different fixed output voltage combinations available (refer to table 'Voltage Options').

    The Linear Regulator being driven from the fixed output voltage of the buck converter (post regulation) translates to high efficiency.

    The device offers superior features and performance for mobile phones and similar portable applications with complex power management systems. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved efficiency over the full load current range. During full-power operation, a fixed-frequency 1.8MHz (typ.) PWM mode drives loads from ~80mA to 750mA max. Hysteretic PFM mode extends the battery life through reduction of the quiescent current during light loads and system standby.

    The LM3687 also features internal protection against over-temperature, current overload and under-voltage conditions.

    Two enable pins allow the separate operation of either the DC-DC or the Linear Regulator alone or both. If the power input voltage for the Linear Regulator VIN_LIN is not sufficiently high (e.g. the DC-DC converter is not enabled or starting up) a startup LDO supplies the Linear Regulator Output from VBATT for 50mA rated load current (Startup Mode). If VIN_LIN is at the required voltage level, the startup LDO is deactivated and the main regulator provides 350mA output current. In shutdown mode (Enable pins pulled low) the device turns off and reduces battery consumption to 0.1µA (typ.).

    The LM3687 is available in a tiny, lead-free (NO PB) 9-bump micro SMD package. A high switching frequency of 1.8MHz (typ.) allows the use of tiny surface-mount components. Only four external components -one inductor and three ceramic capacitors- are required.


    Applications

  • Mobile Phones
  • Hand-Held Radios
  • Personal Digital Assistants
  • Palm-top PCs
  • Portable Instruments
  • Battery Powered Devices



    • Typical Application

     

    ParametersValues
    Input Min Voltage 2.7 Volt
    Input Max Voltage 5.5 Volt
    Output Range Buck: 1.8V; LDO: 1.2-1.5V
    Channels 2 Channels
    Dropout Voltage 0.085 Volt
    Feedback Tolerance 2.5 %
    Output1 VoutMin 1.8 Volt
    Output1 IoutMax 0.75 mA
    Output1 Topology Buck
    Output2 VoutMin 1.2 Volt
    Output2 VoutMax 1.5 Volt
    Output2 IoutMax 0.35 mA
    Output2 Topology LDO
    Special Features integrated LDO and startup mode, internal compensation, ceramic-cap stable, only 4 external components
    Topology Synchronous Buck
    Switching Frequency 1800 kHz
    Adj Switch Frequency No
    Sync Pin No
    RegType Switching Regulator
    Step-Down Yes
    Inverting No
    Flyback No
    Efficiency (peak) 93 %
    Adjustable Output No
    PowerGood / Error Flag No
    On/Off Pin Yes
    Multiple Output Capability Yes
    Temperature Min -30 deg C
    Temperature Max 125 deg C
    PowerWise Yes

    Datasheets
    TitleSizeDateOther
    Language
    LM3687 Step-Down DC-DC Converter with Integrated Low Dropout Regulator and Startup Mode627
    Kbytes    		7-Jul-08   


    Application Notes
    TitleSizeDateOther
    Language
    AN-1647: Application Note 1647 LM3687 Evaluation Board906
    Kbytes    		7-Jul-08 

    Part Number(s)
    (NSID)    		Top ViewAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3687TL-1812/NOPB


    RoHS Status

    MICRO SMD    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    CEACAsia Pacific500
    DIGI-KEYWorldwide370
    MOUSERWorldwide500
    		$0.80 each at 1K+ pcsreel
    of
    250
    LM3687TL-1815/NOPB


    RoHS Status

    MICRO SMD    		Full production
    Lead Time: 6 weeks

    Samples
    DistributorRegionQty
    DIGI-KEYWorldwide415
    MOUSERWorldwide500
    		$0.80 each at 1K+ pcsreel
    of
    250
    LM3687TLX-1812/NOPB


    RoHS Status

    MICRO SMD    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.80 each at 1K+ pcsreel
    of
    3000
    LM3687TLX-1815/NOPB


    RoHS Status

    MICRO SMD    		Full production
    Lead Time: 6 weeks

     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$0.80 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 LM3687.

    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 LM3687 is located at RoHS Status.

    Part Number(s)
    (NSID)    		DescriptionAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3687TL-1812EV
    		LM3687TL-1812 Evaluation BoardFull production


     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		CALLN/A

    Description:

    The LM3687 is a step-down DC-DC converter with an integrated low dropout Linear Regulator optimized for powering ultra-low voltage circuits from a single Li-Ion cell or 3 cell NiMH/NiCd batteries. It provides a dual output with fixed output voltages and combined load current up to 750mA in post regulation mode 1100mA in independent mode of operation, over an input voltage range from 2.7V to 5.5V. There are several different fixed output voltage combinations available.

    The LM3687 evaluation board is designed to enable independent evaluation of the LM3687 electrical performance. Each board is pre-assembled and tested in the factory. The evaluation kit is available in two options: LM3687TL-1812EV and LM3687TL-1815EV. For other voltage options, the device can be ordered from LM3687 product folder on Nationals website.

    Features:

    • 65 µA typical Quiescent Current from VBATT if both regulators are enabled
    • 750mA maximum combined load capability in post regulation setup (DC-DC 400mA + Linear Regulator 350mA)
    • 1100mA maximum total load capability in independent mode of operation (DC-DC: 750mA, Linear Regulator:
      350mA)
    • Operates from a single Li-Ion cell or 3 cell NiMH/NiCd batteries
    • Only four tiny surface-mount external components required (one inductor, three ceramic capacitors)
    • Small 9-bump micro SMD package
    • Over-temperature, current overload and under-voltage protection

    DC-DC Converter:

    • 750mA Maximum load capability
    • 1.8MHz PWM fixed switching frequency (typ.)
    • Automatic PFM/PWM mode switching
    • 27 µ A typ. Quiescent Current
    • Internal synchronous rectification for high efficiency
    • Internal soft start

    Dual Rail Linear Regulator:

    • Startup Mode
    • Load transients <25mVpeak typ.
    • Line transients <1mVpeak typ.
    • Very Low Dropout Voltage: 82mV typ. at 350mA load current
    • 0.7V ≤ VIN_LIN ≤4.5V
    • 10 µA typical IQ from VIN_LIN
    • 350mA maximum load capability

    Applications:

    • Mobile Phones
    • Hand-Held Radios
    • Personal Digital Assistants
    • Palm-top PCs
    • Portable Instruments
    • Battery Powered Devices

    Part Number(s)
    (NSID)    		DescriptionAvailabilityCurrent Reported StockBudgetary PricingPack
    Size
    LM3687TL-1815EV
    		LM3687TL-1815 Evaluation BoardFull production


     
    DistributorRegionQty
    DIGI-KEYWorldwide0
    		$85.00 each1

    Description:

    The LM3687 is a step-down DC-DC converter with an integrated low dropout Linear Regulator optimized for powering ultra-low voltage circuits from a single Li-Ion cell or 3 cell NiMH/NiCd batteries. It provides a dual output with fixed output voltages and combined load current up to 750mA in post regulation mode 1100mA in independent mode of operation, over an input voltage range from 2.7V to 5.5V. There are several different fixed output voltage combinations available.

    The LM3687 evaluation board is designed to enable independent evaluation of the LM3687 electrical performance. Each board is pre-assembled and tested in the factory. The evaluation kit is available in two options: LM3687TL-1812EV and LM3687TL-1815EV. For other voltage options, the device can be ordered from LM3687 product folder on Nationals website.

    Features:

    • 65 µA typical Quiescent Current from VBATT if both regulators are enabled
    • 750mA maximum combined load capability in post regulation setup (DC-DC 400mA + Linear Regulator 350mA)
    • 1100mA maximum total load capability in independent mode of operation (DC-DC: 750mA, Linear Regulator:
      350mA)
    • Operates from a single Li-Ion cell or 3 cell NiMH/NiCd batteries
    • Only four tiny surface-mount external components required (one inductor, three ceramic capacitors)
    • Small 9-bump micro SMD package
    • Over-temperature, current overload and under-voltage protection

    DC-DC Converter:

    • 750mA Maximum load capability
    • 1.8MHz PWM fixed switching frequency (typ.)
    • Automatic PFM/PWM mode switching
    • 27 µ A typ. Quiescent Current
    • Internal synchronous rectification for high efficiency
    • Internal soft start

    Dual Rail Linear Regulator:

    • Startup Mode
    • Load transients <25mVpeak typ.
    • Line transients <1mVpeak typ.
    • Very Low Dropout Voltage: 82mV typ. at 350mA load current
    • 0.7V ≤ VIN_LIN ≤4.5V
    • 10 µA typical IQ from VIN_LIN
    • 350mA maximum load capability

    Applications:

    • Mobile Phones
    • Hand-Held Radios
    • Personal Digital Assistants
    • Palm-top PCs
    • Portable Instruments
    • Battery Powered Devices



    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
    LM3687TL-1812/NOPB

    		2.855
    		MICRO SMD91260DetailDownloadN/A
    		XV
    I SB
    LM3687TL-1815/NOPB

    		2.855
    		MICRO SMD91260DetailDownloadN/A
    		XV
    I S9
    LM3687TLX-1812/NOPB

    		2.855
    		MICRO SMD91260DetailDownloadN/A
    		XV
    I SB
    LM3687TLX-1815/NOPB

    		2.855
    		MICRO SMD91260DetailDownloadN/A
    		XV
    I S9

    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 LM3687.

    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 LM3687 is located at RoHS Status.

    [Information as of 8-Feb-2012]
    Copyright © 2011 National Semiconductor Corporation