SNVS970C March   2013  – October 2014 LM3279

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 System Characteristics
    7. 6.7 System Characteristics Recommended Capacitance Specifications
    8. 6.8 Typical Performance Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Dynamically Adjustable Output Voltage
      2. 7.3.2  Seamless Mode Transition
      3. 7.3.3  Setting The Output Voltage
      4. 7.3.4  General Purpose Outputs
      5. 7.3.5  VCONON
      6. 7.3.6  RDSON Management
      7. 7.3.7  Supply Current Limit
      8. 7.3.8  Reverse Current Limit
      9. 7.3.9  VCON Overvoltage Clamp
      10. 7.3.10 Thermal Overload Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable And Shutdown Mode
      2. 7.4.2 Low-Power Mode
      3. 7.4.3 Standby Mode
      4. 7.4.4 PFM Mode
    5. 7.5 Programming
      1. 7.5.1 Digital Control Serial Bus Interface
      2. 7.5.2 Supported Command Sequences
      3. 7.5.3 Device Enumeration
      4. 7.5.4 I/O
      5. 7.5.5 Control Interface Timing Parameters
    6. 7.6 Registers
      1. 7.6.1 Programmable Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Typical Application Circuit: Digital Control
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Output Current Capability
          2. 8.2.1.2.2 Recommended External Components
            1. 8.2.1.2.2.1 Inductor Selection
            2. 8.2.1.2.2.2 Input Capacitor Selection
          3. 8.2.1.2.3 Output Capacitor Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Typical Application Circuit: Analog Control
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 PCB
        1. 10.1.1.1 Energy Efficiency
        2. 10.1.1.2 EMI
    2. 10.2 Layout Examples
      1. 10.2.1 LM3279 RF Evaluation Board
      2. 10.2.2 Component Placement
    3. 10.3 DSBGA Package Assembly And Use
    4. 10.4 Manufacturing Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • MIPI® RFFE Digital Control Interface
  • High-Efficiency PFM and PWM Modes with Internal Seamless Transition
  • Operates from a Single Li-Ion Cell: 2.7 V to 5.5 V
  • Adjustable Output Voltage:
    • RFFE Digital Control: 0.4 V to 4.2 V
    • Analog Control: 0.5 V to 4.2 V
  • 1-A Maximum Load Capability for VBATT ≥ 3.2 V, VOUT = 3.6 V
  • 2.4-MHz (typ.) Switching Frequency
  • Seamless Buck-Boost Mode Transition
  • Fast Output Voltage Transition: 0.8 V to 4 V in 20 µs
  • High-Efficiency: 95% typ. at VBATT = 3.7 V,
    VOUT = 3.3 V, at 300 mA
  • Input Overcurrent Limit
  • Output Overvoltage Clamp
  • Internal Compensation

2 Applications

  • 3G/4G Smartphones
  • RF PC Cards
  • Tablets, eBooks Readers
  • Battery-Powered RF Devices

3 Description

The LM3279 is a buck-boost DC/DC converter designed to generate output voltages above or below a given input voltage and is particularly suitable for Power Amplifiers operating from single-cell Li-Ion batteries in portable applications.

The LM3279 has four modes of operation: Pulse Width Modulation (PWM), Pulse Frequency Modulation (PFM), standby, and shutdown. During normal conditions, the LM3279 operates in full synchronous PWM mode at 2.4-MHz typical switching frequency, providing seamless transitions between buck and boost operating regimes. Energy-saving PFM mode increases efficiencies and current savings during low-power RF transmission modes. For high-transmit power, the device operates in PWM buck or boost mode, whereas the device can transition between PWM and PFM modes during low-power transmit. The LM3279 can be controlled either via an included MIPI RFFE Digital Control Interface or by using an analog control from an external MCU, offering design flexibility.

The power converter topology enables minimum total solution size by using one small footprint and case size inductor and two surface mount capacitors.

The LM3279 is internally compensated for buck and boost modes of operation thus providing an optimal transient response.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3279 DSBGA (16) 2.529 mm x 2.146 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

LM3279 30173301.gif

PWM Efficiency (VOUT = 2.4 V)

LM3279 30173225.gif