SNOSB48E October   2011  – August 2015 LM3242

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 ESD 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 Timing Requirements
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Circuit Operation
      2. 7.3.2 Internal Synchronous Rectification
      3. 7.3.3 Current Limiting
      4. 7.3.4 Dynamically Adjustable Output Voltage
      5. 7.3.5 Thermal Overload Protection
      6. 7.3.6 Soft Start
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Mode Operation
      2. 7.4.2 Bypass Mode Operation
      3. 7.4.3 ECO Mode Operation
      4. 7.4.4 Sleep Mode Operation
      5. 7.4.5 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Setting The Output Voltage
      2. 8.1.2 FB
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
          1. 8.2.2.1.1 Method 1
          2. 8.2.2.1.2 Method 2
        2. 8.2.2.2 Capacitor Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 PCB Considerations
        1. 10.1.1.1 Energy Efficiency
        2. 10.1.1.2 EMI
      2. 10.1.2 Manufacturing Considerations
      3. 10.1.3 LM3242 Evaluation Board
        1. 10.1.3.1 Component Placement
    2. 10.2 Layout Examples
    3. 10.3 DSBGA Package Assembly and Use
  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 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • 2.7-V to 5.5-V Input Voltage Operating From Single Li-Ion Cell
  • 6-MHz (typical) PWM Switching Frequency
  • 0.4-V to 3.6-V Adjustable Output Voltage
  • 750-mA Maximum Load Capability
    (up to 1 A in Bypass)
  • High Efficiency (95% typical at 3.9 VIN,
    3.3 VOUT at 500 mA)
  • Automatic ECO/PWM/BP Mode Change
  • Current Overload Protection
  • Thermal Overload Protection
  • Soft-Start Function
  • Small Chip Inductor in 0805 (2012) case size

2 Applications

  • Battery-Powered 3G/4G RF PAs
  • Battery-Powered RF Devices
  • Hand-Held Radios
  • RF PC Cards

3 Description

The LM3242 is a DC-DC converter optimized for powering RF power amplifiers (PAs) from a single lithium-ion cell; however, it may be used in many other applications. It steps down an input voltage from 2.7 V to 5.5 V to an adjustable output voltage from 0.4 V to 3.6 V. Output voltage is set using a VCON analog input for controlling power levels and efficiency of the RF PA.

The LM3242 offers five modes of operation. In PWM mode the device operates at a fixed frequency of
6 MHz (typical) which minimizes RF interference when driving medium-to-heavy loads. At light load, the device enters into ECO mode automatically and operates with reduced switching frequency. In ECO mode, the quiescent current is reduced and extends the battery life. Shutdown mode turns the device off and reduces battery consumption to 0.1 µA (typical). In low-battery condition Bypass mode reduces the voltage dropout to less than 50 mV (typical). The part also features a Sleep mode.

The LM3242 is available in a 9-bump lead-free DSBGA package. A high switching frequency (6 MHz) allows use of only three tiny surface-mount components: one inductor and two ceramic capacitors.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3242 DSBGA (9) 1.51 mm × 1.385 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

LM3242 30122201.gif