SLVSJL6A June   2026  – September 2026 LM851772-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Related Products
  6. 5 Pin Configuration and Functions
  7. 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 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Buck-Boost Control Scheme
        1. 8.3.1.1 Buck Mode
        2. 8.3.1.2 Boost Mode
        3. 8.3.1.3 Buck-Boost Mode
      2. 8.3.2  Power Save Mode
      3. 8.3.3  Reference System
        1. 8.3.3.1 Power On Reset and nRST Pin
      4. 8.3.4  Internal VCC Regulators
        1. 8.3.4.1 VCC1 Regulator
        2. 8.3.4.2 VCC2 Regulator
      5. 8.3.5  Enable and Undervoltage Lockout
        1. 8.3.5.1 UVLO
      6. 8.3.6  Error Amplifier and Control
        1. 8.3.6.1 Output Voltage Regulation
        2. 8.3.6.2 Output Voltage Feedback
        3. 8.3.6.3 Voltage Regulation Loop
        4. 8.3.6.4 Dynamic Voltage Scaling
      7. 8.3.7  Output Voltage Discharge
      8. 8.3.8  Peak Current Sensor
      9. 8.3.9  Short Circuit - Hiccup Protection
      10. 8.3.10 Current Monitor/Limiter
        1. 8.3.10.1 Overview
        2. 8.3.10.2 Output Current Limitation
        3. 8.3.10.3 Output Current Monitor
      11. 8.3.11 Oscillator Frequency Selection
      12. 8.3.12 Frequency Synchronization
      13. 8.3.13 Output Voltage Tracking
        1. 8.3.13.1 Analog Voltage Tracking
        2. 8.3.13.2 Digital Voltage Tracking
      14. 8.3.14 Slope Compensation
      15. 8.3.15 Configurable Soft Start
      16. 8.3.16 Drive Pin
      17. 8.3.17 Dual Random Spread Spectrum – DRSS
      18. 8.3.18 Gate Driver
      19. 8.3.19 Cable Drop Compensation (CDC)
      20. 8.3.20 CFG Pin and R2D Interface
      21. 8.3.21 Advanced Monitoring Features
        1. 8.3.21.1  Overview
        2. 8.3.21.2  BUSY
        3. 8.3.21.3  OFF
        4. 8.3.21.4  VOUT
        5. 8.3.21.5  IOUT
        6. 8.3.21.6  INPUT
        7. 8.3.21.7  TEMPERATURE
        8. 8.3.21.8  CML
        9. 8.3.21.9  OTHER
        10. 8.3.21.10 ILIM_OP
        11. 8.3.21.11 nFLT/nINT Pin Output
        12. 8.3.21.12 Status Byte
      22. 8.3.22 Protection Features
        1. 8.3.22.1 Thermal Shutdown (TSD)
        2. 8.3.22.2 Overcurrent Protection
        3. 8.3.22.3 Output Overvoltage Protection 1 (OVP1)
        4. 8.3.22.4 Output Overvoltage Protection 2 (OVP2)
        5. 8.3.22.5 Input Voltage Protection (IVP)
        6. 8.3.22.6 Power Good
        7. 8.3.22.7 Bootstrap Undervoltage Protection
        8. 8.3.22.8 Bootstrap Overvoltage Clamp
        9. 8.3.22.9 CRC - CHECK
    4. 8.4 Device Functional Modes
      1. 8.4.1 Overview
      2. 8.4.2 Logic State Description
    5. 8.5 Programming
      1. 8.5.1 I2C Bus Operation
      2. 8.5.2 Clock Stretching
      3. 8.5.3 Data Transfer Formats
      4. 8.5.4 Single READ From a Defined Register Address
      5. 8.5.5 Sequential READ Starting from a Defined Register Address
      6. 8.5.6 Single WRITE to a Defined Register Address
      7. 8.5.7 Sequential WRITE Starting at a Defined Register Address
  10. 9 LM851772-Q1 Registers
  11. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1  Custom Design With WEBENCH® Tools
        2. 10.2.2.2  Frequency
        3. 10.2.2.3  Feedback Divider
        4. 10.2.2.4  Inductor and Current Sense Resistor Selection
        5. 10.2.2.5  Output Capacitor
        6. 10.2.2.6  Input Capacitor
        7. 10.2.2.7  Slope Compensation
        8. 10.2.2.8  UVLO Divider
        9. 10.2.2.9  Soft-Start Capacitor
        10. 10.2.2.10 nRST and EN/UVLO Pullup Resistor Selection
        11. 10.2.2.11 MOSFETs QH1 and QL1
        12. 10.2.2.12 MOSFETs QH2 and QL2
        13. 10.2.2.13 Loop Compensation
        14. 10.2.2.14 External Component Selection
      3. 10.2.3 Application Curves
    3. 10.3 System Examples
      1. 10.3.1 USB-PD Source with Power Path
      2. 10.3.2 Parallel (Multiphase) Operation
      3. 10.3.3 Wireless Charging Supply
    4. 10.4 Power Supply Recommendations
    5. 10.5 Layout
      1. 10.5.1 Layout Guidelines
        1. 10.5.1.1 Power Stage Layout
        2. 10.5.1.2 Gate Driver Layout
        3. 10.5.1.3 Controller Layout
      2. 10.5.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 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 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

8.3.14 Slope Compensation

The LM851772-Q1 provides slope compensation for stable operation and the best transient performance over a wide operating range.

First, use Equation 23 to calculate a correction factor.

Equation 23. mSC=RCSfSW×Leff×625
  • Where the RCS is the selected peak current sense resistor
  • Leff is the effective (derated), inductance of the inductor at the selected peak current
  • fSWis the selected switching frequency
  • mSCslope compensation correction factor

If the used inductor has no inductance derating disabling the inductor derating with the SEL_INDUC_DERATE in MFR_SPECIFIC_D7 Register Field is possible.

If the used inductor has no inductance derating (meaning: msc × 1.2 or msc × 1.3). By doing so, there is a compromise on the slope compensation and the PSM entry threshold.

Select the slope compensation based on the calculated correction factor through I2C.