SNVS497F November   2008  – September 2016 LM27341 , LM27341-Q1 , LM27342 , LM27342-Q1

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 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 Boost Function
      2. 7.3.2 Low Input Voltage Considerations
      3. 7.3.3 High Output Voltage Considerations
      4. 7.3.4 Frequency Synchronization
      5. 7.3.5 Current Limit
      6. 7.3.6 Frequency Foldback
      7. 7.3.7 Output Overvoltage Protection
      8. 7.3.8 Undervoltage Lockout
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Enable Pin and Shutdown Mode
      2. 7.4.2 Soft-Start Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Inductor Selection
        1. 8.1.1.1 Inductor Calculation Example
      2. 8.1.2  Inductor Material Selection
      3. 8.1.3  Input Capacitor
      4. 8.1.4  Output Capacitor
      5. 8.1.5  Catch Diode
      6. 8.1.6  Boost Diode (Optional)
      7. 8.1.7  Boost Capacitor
      8. 8.1.8  Output Voltage
      9. 8.1.9  Feedforward Capacitor (Optional)
      10. 8.1.10 Calculating Efficiency and Junction Temperature
        1. 8.1.10.1 Schottky Diode Conduction Losses
        2. 8.1.10.2 Inductor Conduction Losses
        3. 8.1.10.3 MOSFET Conduction Losses
        4. 8.1.10.4 MOSFET Switching Losses
        5. 8.1.10.5 IC Quiescent Losses
        6. 8.1.10.6 MOSFET Driver Losses
        7. 8.1.10.7 Total Power Losses
        8. 8.1.10.8 Efficiency Calculation Example
        9. 8.1.10.9 Calculating Junction Temperature
          1. 8.1.10.9.1 Conduction
          2. 8.1.10.9.2 Convection
          3. 8.1.10.9.3 Method 1
          4. 8.1.10.9.4 Method 2
            1. 8.1.10.9.4.1 Method 2 Example
          5. 8.1.10.9.5 Method 3
            1. 8.1.10.9.5.1 Method 3 Example
    2. 8.2 Typical Applications
      1. 8.2.1 LM2734x Configuration From VIN = 7 V to 16 V, VOUT = 5 V For Full Load at 2 MHz
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 LM2734x Configuration From VIN = 7 V to 16 V, VOUT = 5 V For Full Load at 1 MHz
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
      3. 8.2.3 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
      4. 8.2.4 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz With SYNC = GND
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
        3. 8.2.4.3 Application Curves
      5. 8.2.5 LM2734x Configuration From VIN = 5 V to 16 V, VOUT = 3.3 V For Full Load at 2 MHz With SYNC = 1 MHz
        1. 8.2.5.1 Design Requirements
        2. 8.2.5.2 Detailed Design Procedure
        3. 8.2.5.3 Application Curves
      6. 8.2.6 LM2734x Configuration From VIN = 3.3 V to 16 V, VOUT = 1.8 V For Full Load at 2 MHz With SYNC = 1 GND
        1. 8.2.6.1 Design Requirements
        2. 8.2.6.2 Detailed Design Procedure
        3. 8.2.6.3 Application Curves
      7. 8.2.7 LM2734x Configuration From VIN = 3.3 V to 16 V, VOUT = 1.8 V For Full Load at 2 MHz With SYNC = 1 MHz
        1. 8.2.7.1 Design Requirements
        2. 8.2.7.2 Detailed Design Procedure
        3. 8.2.7.3 Application Curves
      8. 8.2.8 LM2734x Configuration From VIN = 3.3 V to 9 V, VOUT = 1.2 V For Full Load at 2 MHz With SYNC = 2 MHz
        1. 8.2.8.1 Design Requirements
        2. 8.2.8.2 Detailed Design Procedure
        3. 8.2.8.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact Layout
      2. 10.1.2 Ground Plane and Shape Routing
      3. 10.1.3 FB Loop
      4. 10.1.4 PCB Summary
    2. 10.2 Layout Example
  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 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Community Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Space-Saving, 3 mm × 3 mm 10-Pin WSON and MSOP-PowerPAD Packages
  • Wide Input Voltage Range: 3 V to 20 V
  • Wide Output Voltage Range: 1 V to 18 V
  • LM27341 Delivers 1.5-A Maximum Output Current
  • LM27342 Delivers 2-A Maximum Output Current
  • High Switching Frequency: 2 MHz
  • Frequency Synchronization:
    1 MHz < fSW < 2.35 MHz
  • 150-mΩ NMOS Switch With Internal Bootstrap Supply
  • 70-nA Shutdown Current
  • Internal Voltage Reference Accuracy of 1%
  • Peak Current-Mode, PWM Operation
  • Thermal Shutdown
  • LM27341-Q1 and LM27342-Q1 are AEC-Q100 Grade 1 Qualified and Manufactured on an Automotive Grade Flow

2 Applications

  • Local 12-V to Vcore Step-Down Converters
  • Radio Power Supply
  • Core Power in HDDs
  • Set-Top Boxes
  • Automotive
  • USB Powered Devices
  • DSL Modems

3 Description

The LM2734x and LM2734x-Q1 regulators are monolithic, high-frequency, PWM step-down DC-DC converters in 10-pin WSON and 10-pin MSOP-PowerPAD packages. They contain all the active functions to provide local DC-DC conversion with fast transient response and accurate regulation in the smallest possible PCB area.

With a minimum of external components, the LM2734x and LM2734x-Q1 are easy to use. The ability to drive 1.5-A or 2-A loads respectively, with an internal 150-mΩ NMOS switch results in the best power density available. The world-class control circuitry allows for on-times as low as 65 ns, thus supporting exceptionally high frequency conversion. Switching frequency is internally set to 2 MHz and synchronizable from 1 to 2.35 MHz, which allows the use of extremely small surface mount inductors and chip capacitors. Even though the operating frequency is very high, efficiencies up to 90% are easy to achieve. External shutdown is included, which features an ultra-low shutdown current of 70 nA. The LM2734x and LM2734x-Q1 use peak current-mode control and internal compensation to provide high-performance regulation over a wide range of operating conditions. Additional features include internal soft-start circuitry to reduce inrush current, pulse-by-pulse current limit, thermal shutdown, and output overvoltage protection.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM2734x
LM2734x-Q1		 MSOP-PowerPAD (10) 4.90 mm × 3.00 mm
WSON (10) 3.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LM27341 LM27342 LM27341-Q1 LM27342-Q1 30005674.gif