SNVSCT4B April   2025  – October 2026 LM72880-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 for the Serial Control Bus
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Input Voltage Range (VIN)
      2. 7.3.2  High-Voltage Bias Supply Regulators (VCC, VDDA)
      3. 7.3.3  Enable (EN/UVLO)
      4. 7.3.4  Switching Frequency
      5. 7.3.5  Dual Random Spread Spectrum (DRSS)
      6. 7.3.6  Soft Start
      7. 7.3.7  Output Voltage and Output Voltage Slew Rate
      8. 7.3.8  Minimum Controllable On-Time
      9. 7.3.9  Dual Loop Architecture
        1. 7.3.9.1 Voltage Loop Error Amplifier
        2. 7.3.9.2 Current Loop Error Amplifier
      10. 7.3.10 Programmable OVP
      11. 7.3.11 Programmable ILIM
      12. 7.3.12 IOUT Monitor
      13. 7.3.13 Cable Drop Compensation
      14. 7.3.14 Slope Compensation
      15. 7.3.15 Shunt Current Sensing
      16. 7.3.16 Hiccup Mode Current Limiting
      17. 7.3.17 Device Configuration (CNFG)
      18. 7.3.18 Pulse Frequency Modulation (PFM) / Synchronization
      19. 7.3.19 Out-of-Audio Operation
      20. 7.3.20 Thermal Shutdown (TSD)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Ready Mode
      4. 7.4.4 Active Mode
      5. 7.4.5 Sleep Mode
    5. 7.5 Programming
      1. 7.5.1 I2C Bus Operation
      2. 7.5.2 Clock Stretching
      3. 7.5.3 Data Transfer Formats
      4. 7.5.4 Single READ from a Defined Register Address
      5. 7.5.5 Sequential READ Starting from a Defined Register Address
      6. 7.5.6 Single WRITE to a Defined Register Address
      7. 7.5.7 Sequential WRITE Starting at a Defined Register Address
  9. 8 LM72880-Q1 Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Power Train Components
        1. 9.1.1.1 Buck Inductor
        2. 9.1.1.2 Output Capacitors
        3. 9.1.1.3 Input Capacitors
        4. 9.1.1.4 EMI Filter
      2. 9.1.2 Error Amplifier and Compensation
      3. 9.1.3 Maximum Ambient Temperature
        1. 9.1.3.1 Derating Curves
    2. 9.2 Typical Application
      1. 9.2.1 High Efficiency, Wide Input, 400kHz, Synchronous Buck Regulator
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2 Buck Inductor
          3. 9.2.1.2.3 Current-Sense Resistance
          4. 9.2.1.2.4 Output Capacitors
          5. 9.2.1.2.5 Input Capacitors
          6. 9.2.1.2.6 Compensation Components
        3. 9.2.1.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Thermal Design and Layout
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 Custom Design With WEBENCH® Tools
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
        1. 10.2.1.1 PCB Layout Resources
        2. 10.2.1.2 Thermal Design Resources
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

7.3.1 Input Voltage Range (VIN)

The LM72880-Q1 operational input voltage range is from 4.5V to 80V. The device is intended for step-down conversions from 12V, 24V and 48V automotive supply rails. The LM72880-Q1 uses internal LDOs to provide a 5V to 8V VCC bias rail and a 5V VDDA rail for the gate drive and control circuits.

In high input voltage applications, make sure that the VIN and SW pins do not exceed the absolute maximum voltage rating of 87.5V during line or load transient events. Voltage excursions that exceed the absolute maximum ratings of these pins can damage the IC. Follow PCB board layout recommendations and use high-quality input bypass capacitors to minimize voltage overshoot and ringing.

As VIN approaches VOUT, the LM72880-Q1 skips tOFF cycles to allow the controller to extend the duty cycle up to approximately 99%. Refer to Figure 7-1.

Use Equation 1 to calculate when the LM72880-Q1 enters dropout mode.

Equation 1. VIN=VOUT× tPtP - tOFF
  • tP = oscillator period
  • tOFF = minimum off time
LM72880-Q1 Dropout Mode Operation Figure 7-1 Dropout Mode Operation