SNVSCL2A December   2024  – August 2025 LM51770 , LM517701

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 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 Timing Requirements
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Gate Driver Rise Time and Fall Time
    2. 7.2 Gate Driver Dead (Transition) Time
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Power-On Reset (POR System)
      2. 8.3.2  Buck-Boost Control Scheme
        1. 8.3.2.1 Boost Mode
        2. 8.3.2.2 Buck Mode
        3. 8.3.2.3 Buck-Boost Mode
      3. 8.3.3  Power Save Mode
      4. 8.3.4  Supply Voltage Selection – VMAX Switch
      5. 8.3.5  Enable and Undervoltage Lockout
      6. 8.3.6  Oscillator Frequency Selection
      7. 8.3.7  Frequency Synchronization
      8. 8.3.8  Voltage Regulation Loop
      9. 8.3.9  Output Voltage Tracking
      10. 8.3.10 Slope Compensation
      11. 8.3.11 Configurable Soft Start
      12. 8.3.12 Peak Current Sensor
      13. 8.3.13 Current Monitoring and Current Limit Control Loop
      14. 8.3.14 Short Circuit - Hiccup Protection
      15. 8.3.15 nFLT Pin and Protections
      16. 8.3.16 Device Configuration Pin
      17. 8.3.17 Dual Random Spread Spectrum – DRSS
      18. 8.3.18 Gate Driver
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1  Custom Design with WEBENCH Tools
        2. 9.2.2.2  Frequency
        3. 9.2.2.3  Feedback Divider
        4. 9.2.2.4  Inductor and Current Sense Resistor Selection
        5. 9.2.2.5  Slope Compensation
        6. 9.2.2.6  Output Capacitor
        7. 9.2.2.7  Input Capacitor
        8. 9.2.2.8  UVLO Divider
        9. 9.2.2.9  Soft-Start Capacitor
        10. 9.2.2.10 MOSFETs QH1 and QL1
        11. 9.2.2.11 MOSFETs QH2 and QL2
        12. 9.2.2.12 Output Voltage Frequency Compensation
        13. 9.2.2.13 External Component Selection
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
      1. 9.3.1 Bi-Directional Power Backup
      2. 9.3.2 Parallel (Multiphase) Operation
      3. 9.3.3 External Gate Driver with Logic Level High Side Gate Signals
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
        1. 9.5.1.1 Power Stage Layout
        2. 9.5.1.2 Gate Driver Layout
        3. 9.5.1.3 Controller Layout
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
      2. 10.1.2 Development Support
        1. 10.1.2.1 Custom Design with WEBENCH Tools
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1.     86

4 Device Comparison

Table 4-1 Device Comparison
FUNCTION LM51770 LM517701 LM5177 LM251772 LM51772
Maximum Recommended Input Voltage 78V 78V 60V 36V 55V
Absolute Maximum Input Voltage 85V 85V 85V 48V 59V
Maximum Recommended Switching Frequency 1.8MHz 1.8MHz 600kHz 600kHz 2.2MHz
Peak current sense threshold 50mV 75mV 50mV 50mV 50mV
Default Output Voltage Value n/a 24V n/a 5.1V 12V
Default Output Current Limit Value n/a n/a n/a 900mA 5A
I2C interface no no no yes yes
Output Start-up State Without Programming Enabled Enabled Enabled Disabled Enabled
PSM - Automatic Conduction Mode yes no no yes yes
PSM - Programmable Conduction Mode no no no no yes
Output Discharge no no no yes yes
Input voltage regulation with external circuit with external circuit with external circuit yes yes
Logic output pins for external gate driver yes yes yes no no
Analog Current Limit Setting Pin no no no no yes
Tj Temperature Range -40°C to 125°C -40°C to 125°C -40°C to 125°C 0°C to 70°C -40°C to 125°C