SNVSC40E August   2021  – September 2023 LMR38020

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 System Characteristics
    7. 7.7 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Fixed Frequency Peak Current Mode Control
      2. 8.3.2  Adjustable Output Voltage
      3. 8.3.3  Enable
      4. 8.3.4  Switching Frequency and Synchronization (RT/SYNC)
      5. 8.3.5  Power-Good Flag Output
      6. 8.3.6  Minimum On Time, Minimum Off Time, and Frequency Foldback
      7. 8.3.7  Bootstrap Voltage
      8. 8.3.8  Overcurrent and Short Circuit Protection
      9. 8.3.9  Soft Start
      10. 8.3.10 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Auto Mode
      2. 8.4.2 Forced PWM Operation
      3. 8.4.3 Dropout
      4. 8.4.4 Minimum Switch On Time
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Choosing the Switching Frequency
        3. 9.2.2.3 FB for Adjustable Output
        4. 9.2.2.4 Inductor Selection
        5. 9.2.2.5 Output Capacitor Selection
        6. 9.2.2.6 Input Capacitor Selection
        7. 9.2.2.7 CBOOT
        8. 9.2.2.8 External UVLO
        9. 9.2.2.9 Maximum Ambient Temperature
      3. 9.2.3 Application Curves
    3. 9.3 Best Design Practices
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
        1. 9.5.1.1 Ground and Thermal Considerations
      2. 9.5.2 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. 10.1.2 Third-Party Products Disclaimer
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    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. 11Mechanical, Packaging, and Orderable Information

9.2 Typical Application

Figure 9-1 shows a typical application circuit for the LMR38020. This device is designed to function over a wide range of external components and system parameters. However, the internal compensation is optimized for a certain range of external inductance and output capacitance. As a quick-start guide, Table 9-1 provides typical component values for a range of the most common output voltages.

GUID-20210827-SS0I-N7RT-6KSH-GZQQ29H1R968-low.svg Figure 9-1 Example Application Circuit
Table 9-1 Typical External Component Values for 2-A Output Current
ƒSW (kHz)

VIN (V) Typical

VOUT (V)L (µH)NOMINAL COUT (RATED CAPACITANCE)MINIMUM COUT (RATED CAPACITANCE)RFBT (Ω)RFBB (Ω)
400

48

5

15

3 × 22 µF

2 × 22 µF100 k24.9 k

1000

24

5

6.8

2 × 22 µF2 × 15 µF100 k24.9 k
400

48

12

33

1× 22 µF

1 × 15 µF100 k9.09 k

1000

24

12

10

2 × 10 µF1 × 10 µF100 k9.09 k
500

48

24

47

1 × 22 µF1 × 15 µF100 k4.32 k