SNVS615K January   2010  – February 2018 LM27402

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Timing Requirements
    7. 6.7 Switching Characteristics
    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  Wide Input Voltage Range
      2. 7.3.2  UVLO
      3. 7.3.3  Precision Enable
      4. 7.3.4  Soft-Start and Voltage Tracking
      5. 7.3.5  Output Voltage Setpoint and Accuracy
      6. 7.3.6  Voltage-Mode Control
      7. 7.3.7  Power Good
      8. 7.3.8  Inductor-DCR-Based Overcurrent Protection
      9. 7.3.9  Current Sensing
      10. 7.3.10 Power MOSFET Gate Drivers
      11. 7.3.11 Pre-Bias Start-up
    4. 7.4 Device Functional Modes
      1. 7.4.1 Fault Conditions
        1. 7.4.1.1 Thermal Protection
        2. 7.4.1.2 Current Limit
        3. 7.4.1.3 Negative Current Limit
        4. 7.4.1.4 Undervoltage Threshold (UVT)
        5. 7.4.1.5 Overvoltage Threshold (OVT)
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Converter Design
      2. 8.1.2  Inductor Selection (L)
      3. 8.1.3  Output Capacitor Selection (COUT)
      4. 8.1.4  Input Capacitor Selection (CIN)
      5. 8.1.5  Using Precision Enable
      6. 8.1.6  Setting the Soft-Start Time
      7. 8.1.7  Tracking
      8. 8.1.8  Setting the Switching Frequency
      9. 8.1.9  Setting the Current Limit Threshold
      10. 8.1.10 Control Loop Compensation
      11. 8.1.11 MOSFET Gate Drivers
      12. 8.1.12 Power Loss and Efficiency Calculations
        1. 8.1.12.1 Power MOSFETs
        2. 8.1.12.2 High-Side Power MOSFET
        3. 8.1.12.3 Low-Side Power MOSFET
        4. 8.1.12.4 Gate-Charge Loss
        5. 8.1.12.5 Input and Output Capacitor ESR Losses
        6. 8.1.12.6 Inductor Losses
        7. 8.1.12.7 Controller Losses
        8. 8.1.12.8 Overall Efficiency
    2. 8.2 Typical Applications
      1. 8.2.1 Example Circuit 1
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Example Circuit 2
      3. 8.2.3 Example Circuit 3
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Stage Layout
      2. 10.1.2 Gate Drive Layout
      3. 10.1.3 Controller Layout
      4. 10.1.4 Thermal Design and Layout
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6.8 Typical Performance Characteristics

Unless otherwise stated, all data sheet curves were recorded using Example Circuit 1. VIN = 12 V.
LM27402 30092679.pngFigure 1. Efficiency (Vout = 1.5 V)
LM27402 30092603.pngFigure 3. Efficiency (Vout = 3.3 V, Example Circuit 2)
LM27402 30092667.pngFigure 5. Line Regulation (Vout = 1.5 V)
LM27402 30092609.pngFigure 7. Frequency vs Temperature (RFADJ = 20 kΩ)
LM27402 30092663.pngFigure 9. CS– Current Source vs Temperature
LM27402 30092635.pngFigure 11. CS– Current Source Compliance Voltage
LM27402 30092636.png
Horizontal Scale: 2 ms/DIV
Figure 13. Start-up Waveforms
LM27402 30092692.png
Horizontal Scale: 2 ms/DIV
Figure 15. OCP Hiccup
LM27402 30092694.png
Horizontal Scale: 2 ms/DIV
Figure 17. Tracking
LM27402 30092689.pngFigure 19. Quiescent Current vs Temperature
LM27402 30092680.pngFigure 2. Efficiency (Vout = 5 V, Example Circuit 2)
LM27402 30092653.pngFigure 4. Load Regulation (Vout = 1.5 V)
LM27402 30092607.pngFigure 6. VDD Voltage vs Temperature (IVDD = 25 mA)
LM27402 30092639.pngFigure 8. Frequency vs RFADJ
LM27402 30092638.pngFigure 10. Deadtime vs Temperature
LM27402 30092637.png
Horizontal Scale: 100 µs/DIV
Figure 12. Load Transient
LM27402 30092691.png
Horizontal Scale: 2 ms/DIV
Figure 14. Pre-Bias Start-up
LM27402 30092693.png
Horizontal Scale: 400 ns/DIV
Figure 16. Frequency Synchronization
LM27402 30092634.pngFigure 18. Shutdown Quiescent Current vs Temperature
LM27402 30092688.pngFigure 20. Feedback Voltage vs Temperature