SLVSJL6 June   2026 LM851772-Q1

ADVANCE INFORMATION  

  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
  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 Boot-Strap Undervoltage Protection
        8. 8.3.22.8 Boot-strap 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 Pull-up 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 USB-PD Source with Power Path
    4. 10.4 Parallel (Multiphase) Operation
    5. 10.5 Wireless Charging Supply
    6. 10.6 Power Supply Recommendations
    7. 10.7 Layout
      1. 10.7.1 Layout Guidelines
        1. 10.7.1.1 Power Stage Layout
        2. 10.7.1.2 Gate Driver Layout
        3. 10.7.1.3 Controller Layout
      2. 10.7.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Tape and Reel Information
    2.     132

6.7 Typical Characteristics

The following conditions apply (unless otherwise noted): TJ = 25°C; V(VCC2) = 5V

LM851772-Q1 Switching Frequency Versus RT ResistanceFigure 6-1 Switching Frequency Versus RT Resistance
LM851772-Q1 FB Pin Reference Voltage Versus TemperatureFigure 6-3 FB Pin Reference Voltage Versus Temperature
LM851772-Q1 Shutdown Current Into VIN Versus Pin Voltage VEN/UVLO = 0V ,V(VIN) = 12V, V(BIAS) = 0VFigure 6-5 Shutdown Current Into VIN Versus Pin Voltage
VEN/UVLO = 0V ,V(VIN) = 12V, V(BIAS) = 0V
LM851772-Q1 Shutdown Current Into BIAS Versus Temperature VEN/UVLO = 0V ,V(VIN) = 3.5V,V(BIAS) = 12VFigure 6-7 Shutdown Current Into BIAS Versus Temperature
VEN/UVLO = 0V ,V(VIN) = 3.5V,V(BIAS) = 12V
LM851772-Q1 Quiescent Current Into BIAS Versus BIAS V(BIAS) = 12V , V(VIN) = 3.5V Figure 6-9 Quiescent Current Into BIAS Versus BIAS
V(BIAS) = 12V , V(VIN) = 3.5V
LM851772-Q1 VCC2 LDO Output Voltage Versus VCC2 Load Current V(VIN) = 3.5V, V(BIAS) = 12VFigure 6-11 VCC2 LDO Output Voltage Versus VCC2 Load Current
V(VIN) = 3.5V, V(BIAS) = 12V
LM851772-Q1 Soft-Start Current Versus Temperature Figure 6-13 Soft-Start Current Versus Temperature
LM851772-Q1 Hysteresis Current on EN/UVLO Versus Temperature Figure 6-15 Hysteresis Current on EN/UVLO Versus Temperature
LM851772-Q1 Buck Minimum On-time Versus Switching FrequencyFigure 6-17 Buck Minimum On-time Versus Switching Frequency
LM851772-Q1 Boost Minimum On-time Versus Switching FrequencyFigure 6-19 Boost Minimum On-time Versus Switching Frequency
LM851772-Q1 Gate Driver Transition (Dead) Time Versus Switching Frequency SEL_MIN_DEADTIME_GDRV = 0b01,SEL_SCALE_DT = 0b0, EN_CONST_TDEAD = 0b0Figure 6-21 Gate Driver Transition (Dead) Time Versus Switching Frequency
SEL_MIN_DEADTIME_GDRV = 0b01,SEL_SCALE_DT = 0b0, EN_CONST_TDEAD = 0b0
LM851772-Q1 Peak Current Limit Threshold Voltage Versus TemperatureFigure 6-23 Peak Current Limit Threshold Voltage Versus Temperature
LM851772-Q1 CSB Input Current Versus Temperature Figure 6-25 CSB Input Current Versus Temperature
LM851772-Q1 Average Current Limit Threshold Voltage Versus Temperature ILIM_THRESHOLD = 0x3CFigure 6-27 Average Current Limit Threshold Voltage Versus Temperature
ILIM_THRESHOLD = 0x3C
LM851772-Q1 Switching Frequency Versus Temperature R(RT) = 75KΩ Figure 6-2 Switching Frequency Versus Temperature
R(RT) = 75KΩ
LM851772-Q1 FB Pin Reference Voltage Versus VO Register DAC-CodeFigure 6-4 FB Pin Reference Voltage Versus VO Register DAC-Code
LM851772-Q1 Shutdown Current Into VIN Versus Temperature VEN/UVLO = 0V ,V(VIN) = 12V,V(BIAS) = 0VFigure 6-6 Shutdown Current Into VIN Versus Temperature
VEN/UVLO = 0V ,V(VIN) = 12V,V(BIAS) = 0V
LM851772-Q1 Quiescent Current Into BIAS Versus BIAS Pin Voltage V(VIN) = 3.5V Figure 6-8 Quiescent Current Into BIAS Versus BIAS Pin Voltage
V(VIN) = 3.5V
LM851772-Q1 Standby Current Into BIAS Versus Temperature V(VIN) = 3.5V V(VIN) = 12V Figure 6-10 Standby Current Into BIAS Versus Temperature
V(VIN) = 3.5V V(VIN) = 12V
LM851772-Q1 VCC2 LDO Output Voltage Versus BIAS Voltage V(VIN) = 2.5VFigure 6-12 VCC2 LDO Output Voltage Versus BIAS Voltage
V(VIN) = 2.5V
LM851772-Q1 EN/UVLO Threshold Versus Temperature Figure 6-14 EN/UVLO Threshold Versus Temperature
LM851772-Q1 Buck Minimum Off-time Versus Switching Frequency Figure 6-16 Buck Minimum Off-time Versus Switching Frequency
LM851772-Q1 Boost Minimum Off-time Versus Switching FrequencyFigure 6-18 Boost Minimum Off-time Versus Switching Frequency
LM851772-Q1 Buck Minimum Duty-cycle for PSM Operation Versus Switching Frequency (SYNC_OUT = Enabled)Figure 6-20 Buck Minimum Duty-cycle for PSM Operation Versus Switching Frequency (SYNC_OUT = Enabled)
LM851772-Q1 Gate Driver Transition (Dead) Time versus Switching Frequency f(sw) = 100kHz ,SEL_MIN_DEADTIME_GDRV = 0b01, EN_CONST_TDEAD = 0b0, Turn Low-Side off, Turn High-Side onFigure 6-22 Gate Driver Transition (Dead) Time versus Switching Frequency
f(sw) = 100kHz ,SEL_MIN_DEADTIME_GDRV = 0b01, EN_CONST_TDEAD = 0b0, Turn Low-Side off, Turn High-Side on
LM851772-Q1 CSA Input Current Versus TemperatureFigure 6-24 CSA Input Current Versus Temperature
LM851772-Q1 Average Current Limit Threshold Voltage Versus Temperature ILIM_THRESHOLD = 0x64Figure 6-26 Average Current Limit Threshold Voltage Versus Temperature
ILIM_THRESHOLD = 0x64
LM851772-Q1 Average Current Limit Threshold Voltage Versus Temperature ILIM_THRESHOLD = 0x14Figure 6-28 Average Current Limit Threshold Voltage Versus Temperature
ILIM_THRESHOLD = 0x14