SNVSBU7 September   2020 LM34966-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
    1.     Pin 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  Line Undervoltage Lockout (UVLO/SYNC/EN Pin)
      2. 8.3.2  High Voltage VCC Regulator (BIAS, VCC Pin)
      3. 8.3.3  Soft Start (SS Pin)
      4. 8.3.4  Switching Frequency (RT Pin)
      5. 8.3.5  Clock Synchronization (UVLO/SYNC/EN Pin)
      6. 8.3.6  Current Sense and Slope Compensation (CS Pin)
      7. 8.3.7  Current Limit and Minimum On-time (CS Pin)
      8. 8.3.8  Feedback and Error Amplifier (FB, COMP Pin)
      9. 8.3.9  Power-Good Indicator (PGOOD Pin)
      10. 8.3.10 Hiccup Mode Overload Protection
      11. 8.3.11 Maximum Duty Cycle Limit and Minimum Input Supply Voltage
      12. 8.3.12 MOSFET Driver (GATE Pin)
      13. 8.3.13 Overvoltage Protection (OVP)
      14. 8.3.14 Thermal Shutdown (TSD)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Run Mode
  9. 9 Application and Implementation
    1. 9.1 Power-On Hours (POH)
    2. 9.2 Application Information
    3. 9.3 Typical Application
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
        1. 9.3.2.1 Custom Design With WEBENCH® Tools
        2. 9.3.2.2 Recommended Components
        3. 9.3.2.3 Inductor Selection (LM)
        4. 9.3.2.4 Output Capacitor (COUT)
        5. 9.3.2.5 Input Capacitor
        6. 9.3.2.6 MOSFET Selection
        7. 9.3.2.7 Diode Selection
        8. 9.3.2.8 Efficiency Estimation
      3. 9.3.3 Application Curve
    4. 9.4 System Examples
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
        1. 12.1.2.1 Custom Design With WEBENCH® Tools
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.3.2.6 MOSFET Selection

The MOSFET gate driver of the device is sourced from the VCC. The maximum gate charge is limited by the 35-mA VCC sourcing current limit.

A leadless package is preferred for high switching-frequency designs. The MOSFET gate capacitance should be small enough so that the gate voltage is fully discharged during the off-time.