SNVSCQ9 November   2025 LM68425-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Device Comparison Table
  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 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 Output Voltage Selection
      2. 7.3.2 EN Pin and Use as VIN UVLO
      3. 7.3.3 Mode Selection
        1. 7.3.3.1 MODE/SYNC/TEMP Pin Uses for Synchronization
        2. 7.3.3.2 Clock Locking
      4. 7.3.4 Adjustable Switching Frequency
      5. 7.3.5 Dual Random Spread Spectrum (DRSS)
      6. 7.3.6 Internal LDO, VCC UVLO, and BIAS Input
      7. 7.3.7 Bootstrap Voltage (BST Pin)
      8. 7.3.8 Soft Start and Recovery From Dropout
      9. 7.3.9 Safety Features
        1. 7.3.9.1 Power-Good Monitor
        2. 7.3.9.2 Redundant VOUT Monitor
        3. 7.3.9.3 Fault Output
        4. 7.3.9.4 Voltage Reference Monitor
        5. 7.3.9.5 Start-Up Diagnostics
        6. 7.3.9.6 Overcurrent and Short-Circuit Protection
        7. 7.3.9.7 Hiccup
        8. 7.3.9.8 Thermal Shutdown
        9. 7.3.9.9 Redundant Temperature Sensor
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Active Mode
        1. 7.4.2.1 Peak Current Mode Operation
        2. 7.4.2.2 Auto Mode Operation
          1. 7.4.2.2.1 Diode Emulation
        3. 7.4.2.3 FPWM Mode Operation
        4. 7.4.2.4 Dropout
        5. 7.4.2.5 Recovery from Dropout
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Choosing the Switching Frequency
        3. 8.2.2.3 FB for Adjustable or Fixed Output Voltage Mode
        4. 8.2.2.4 Inductor Selection
        5. 8.2.2.5 Output Capacitor Selection
        6. 8.2.2.6 Input Capacitor Selection
        7. 8.2.2.7 CBOOT
        8. 8.2.2.8 External UVLO
        9. 8.2.2.9 Maximum Ambient Temperature
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
        1. 8.5.1.1 Ground and Thermal Considerations
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2 Typical Application

Figure 8-1 and Figure 8-2 show typical application circuits for the LM684x5-Q1, when using the adjustable output mode or the fixed output mode, respectively. This device is designed to function over a wide range of external components and system parameters. However, the internal compensation is designed for a certain range of external inductance and output capacitance. As a quick-start guide, Table 8-1 provide typical component values for a range of application parameters. The component values in these table represent stable designs and are not necessarily optimized. Note that the designs in these tables are based on a typical input voltage of 12V; or 36V for the 24V outputs.

LM68415-Q1 LM68425-Q1 Example Application Circuit for Adjustable Output Voltage Mode With LM684x5-Q1 Figure 8-1 Example Application Circuit for Adjustable Output Voltage Mode With LM684x5-Q1
LM68415-Q1 LM68425-Q1 Example Application Circuit for Fixed Output Voltage Mode With LM684x5-Q1 Figure 8-2 Example Application Circuit for Fixed Output Voltage Mode With LM684x5-Q1
(1) Please note all COUT values are the derated output capacitor values in the tables.
Table 8-1 Typical External Components for LM6x425 in Adjustable Output Voltage Mode
OUTPUT VOLTAGE FREQUENCY L COUT(1) RFBT RFBB CFF
3.3V 400kHz 8.2μH 75μF 100kΩ 31.6kΩ 20pF
5V 400kHz 10μH 50μF 100kΩ 19.1kΩ 20pF
400kHz 47μH 15μF 205kΩ 7.15kΩ
3.3V 2200kHz 1.5μH 25μF 100kΩ 31.6kΩ 5pF
5V 2200kHz 1.5μH 15μF 100kΩ 19.1kΩ 5pF
2200kHz 8.2μH 10μF 205kΩ 7.15kΩ