SNVS449O June   2007  – April 2015 LM3668

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Buck Operation
      2. 8.3.2 Boost Operation
      3. 8.3.3 Internal Synchronous Rectification
      4. 8.3.4 Current Limit Protection
      5. 8.3.5 Undervoltage Protection
      6. 8.3.6 Short Circuit Protection
      7. 8.3.7 Shutdown
      8. 8.3.8 Thermal Shutdown
      9. 8.3.9 Start-Up
    4. 8.4 Device Functional Modes
      1. 8.4.1 PWM Operation
      2. 8.4.2 PFM Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 MODE/SYNC Pin
      2. 9.1.2 VSEL Pin
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 Maximum Current
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inductor Selection
        2. 9.2.2.2 Input Capacitor Selection
        3. 9.2.2.3 Output Capacitor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Documentation Support
        1. 12.1.2.1 Related Documentation
    2. 12.2 Trademarks
    3. 12.3 Electrostatic Discharge Caution
    4. 12.4 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

1 Features

  • 45-µA Typical Quiescent Current
  • For 2.8-V-3.3-V and 3-V-3.4-V Versions:
    • 1-A Maximum Load Current for
      VIN = 2.8 V to 5.5 V
    • 800-mA Maximum Load Current for
      VIN = 2.7 V
    • 600-mA Maximum Load Current for
      VIN = 2.5 V
  • For 4.5 V-5 V
    • 1-A Maximum Load Current for
      VIN = 3.9 V to 5.5 V
    • 800-mA Maximum Load Current for
      VIN = 3.4 V to 3.8 V
    • 700-mA Maximum Load Current for
      VIN = 3 V to 3.3 V
    • 600-mA Maximum Load Current for
      VIN = 2.7 V to 2.9 V
  • 2.2-MHz PWM Fixed Switching Frequency (Typical)
  • Automatic PFM-PWM Mode or Forced PWM Mode
  • Wide Input Voltage Range: 2.5 V to 5.5 V
  • Internal Synchronous Rectification for High Efficiency
  • Internal Soft Start: 600-µs Maximum Start-Up Time After VIN Settled
  • 0.01-µA Typical Shutdown Current
  • Current Overload and Thermal Shutdown Protection
  • Frequency Sync Pin: 1.6 MHz to 2.7 MHz

    • Typical Application Circuit

    LM3668 20191401.gif

2 Applications

  • Handset Peripherals
  • MP3 Players
  • Pre-Regulation for Linear Regulators
  • PDAs
  • Portable Hard Disk Drives
  • WiMax Modems

3 Description

The LM3668 is a synchronous buck-boost DC-DC converter optimized for powering low voltage circuits from a Li-Ion battery and input voltage rails between 2.5 V and 5.5 V. It has the capability to support up to 1-A output current over the output voltage range. The LM3668 regulates the output voltage over the complete input voltage range by automatically switching between buck or boost modes depending on the input voltage.

The LM3668 has 2 N-channel MOSFETS and 2 P-channel MOSFETS arranged in a topology that provides continuous operation through the buck and boost operating modes. There is a MODE pin that allows the user to choose between an intelligent automatic PFM-PWM mode operation and forced PWM operation. During PWM mode, a fixed-frequency 2.2 MHz (typical) is used. PWM mode drives load up to 1 A. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 45 µA (typical) at light loads during system standby. Internal synchronous rectification provides high efficiency. In shutdown mode (EN pin pulled low), the device turns off and reduces battery consumption to 0.01 µA (typical).

A high switching frequency of 2.2 MHz (typical) allows the use of tiny surface-mount components including a 2.2-µH inductor, a 10-µF input capacitor, and a 22-µF output capacitor.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3668 WSON (12) 3.00 mm x 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

4 Revision History

Changes from N Revision (August 2014) to O Revision

  • Changed RθJA value from 34 to 47.3; change 20 PINS to 12 PINS in header; add additional thermal informationGo

Changes from M Revision (May 2013) to N Revision

  • Added Pin Configuration and Functions section, Handling Rating table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go

Changes from L Revision (April 2013) to M Revision

  • Changed layout of National Data Sheet to TI formatGo