SLVSGN5A October   2022  – November 2025 LM51231-Q1

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Device Enable/Disable (EN, VH Pin)
      2. 6.3.2  High Voltage VCC Regulator (BIAS, VCC Pin)
      3. 6.3.3  Light Load Switching Mode Selection (MODE Pin)
      4. 6.3.4  VOUT Range Selection (RANGE Pin)
      5. 6.3.5  Line Undervoltage Lockout (UVLO Pin)
      6. 6.3.6  Fast Restart using VCC HOLD (VH Pin)
      7. 6.3.7  Adjustable Output Regulation Target (VOUT, TRK, VREF Pin)
      8. 6.3.8  Overvoltage Protection (VOUT Pin)
      9. 6.3.9  Power Good Indicator (PGOOD Pin)
      10. 6.3.10 Dynamically Programmable Switching Frequency (RT)
      11. 6.3.11 External Clock Synchronization (SYNC Pin)
      12. 6.3.12 Programmable Spread Spectrum (DITHER Pin)
      13. 6.3.13 Programmable Soft-start (SS Pin)
      14. 6.3.14 Wide Bandwidth Transconductance Error Amplifier and PWM (TRK, COMP Pin)
      15. 6.3.15 Current Sensing and Slope Compensation (CSP, CSN Pin)
      16. 6.3.16 Constant Peak Current Limit (CSP, CSN Pin)
      17. 6.3.17 Maximum Duty Cycle and Minimum Controllable On-time Limits
      18. 6.3.18 MOSFET Drivers, Integrated Boot Diode, and Hiccup Mode Fault Protection (LO, HO, HB Pin)
      19. 6.3.19 Thermal Shutdown Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Device Status
        1. 6.4.1.1 Shutdown Mode
        2. 6.4.1.2 Configuration Mode
        3. 6.4.1.3 Active Mode
        4. 6.4.1.4 Bypass Mode
          1. 6.4.1.4.1 Bypass DE mode
          2. 6.4.1.4.2 Bypass FPWM
      2. 6.4.2 Light Load Switching Mode
        1. 6.4.2.1 Forced PWM (FPWM) Mode
        2. 6.4.2.2 Diode Emulation (DE) Mode
        3. 6.4.2.3 Forced Diode Emulation Operation in FPWM Mode
  8. Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Ideas
      4. 7.2.4 Application Curves
    3. 7.3 System Example
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

Typical Characteristics

LM51231-Q1 Frequency vs RT
                                                  ResistanceFigure 5-1 Frequency vs RT Resistance
LM51231-Q1 RT Frequency vs
                        Temperature (RT = 220kΩ, f SW =
                        100kHz)Figure 5-3 RT Frequency vs Temperature
(RT = 220kΩ, f SW = 100kHz)
LM51231-Q1 VBIAS vs IBIAS (active mode) Figure 5-5 VBIAS vs IBIAS (active mode)
LM51231-Q1 VVOUT vs
                            IVOUT (bypass mode) Figure 5-7 VVOUT vs IVOUT (bypass mode)
LM51231-Q1 VVCC vs
                                                  IVCCFigure 5-9 VVCC vs IVCC
LM51231-Q1 Peak
                        current limit threshold VCLTH vs Temperature, VCSP =
                        3V Figure 5-11 Peak current limit threshold VCLTH vs Temperature, VCSP = 3V
LM51231-Q1 ICSP vs
                            VCSP (active mode)Figure 5-13 ICSP vs VCSP (active mode)
LM51231-Q1 VREF vs TemperatureFigure 5-15 VREF vs Temperature
LM51231-Q1 DMAX vs Switching
                        FrequencyFigure 5-17 DMAX vs Switching Frequency
LM51231-Q1 RT
                        Frequency vs Temperature (RT = 9.09kΩ, f
                            SW = 2.2MHz)Figure 5-2 RT Frequency vs Temperature
(RT = 9.09kΩ, f SW = 2.2MHz)
LM51231-Q1 VBIAS vs IBIAS (shutdown mode)Figure 5-4 VBIAS vs IBIAS (shutdown mode)
LM51231-Q1 Bypass DEMFigure 5-6 Bypass DEM
LM51231-Q1 VBIAS vs
                                                  VVCCFigure 5-8 VBIAS vs VVCC
LM51231-Q1 Peak
                        current limit threshold VCLTH vs VCSPFigure 5-10 Peak current limit threshold VCLTH vs VCSP
LM51231-Q1 Bypass forward current
                        threshold, VCS-FWD vs Temperature , VCSP = 3VFigure 5-12 Bypass forward current threshold, VCS-FWD vs Temperature , VCSP = 3V
LM51231-Q1 ICSP vs temperature (active mode)  VCSP = 3VFigure 5-14 ICSP vs temperature (active mode)
VCSP = 3V
LM51231-Q1 VVCC vs Peak
                                                  Driver Current Figure 5-16 VVCC vs Peak Driver Current