SNVA991 October   2022 LM5123-Q1


  1.   How to Design a Boost Converter Using LM5123
  2.   Trademarks
  3. 1Design Example
  4. 2Calculations and Component Selection
    1. 2.1  Switching Frequency
    2. 2.2  Initial Inductor Calculation
    3. 2.3  Current Sense Resistor Selection
    4. 2.4  Inductor Selection
    5. 2.5  Output Capacitor Selection
    6. 2.6  Input Capacitor Selection
    7. 2.7  Feedback Resistor Selection
    8. 2.8  UVLO Resistor Selection
    9. 2.9  Soft-Start Capacitor Selection
    10. 2.10 Control Loop Compensation
      1. 2.10.1 Crossover Frequency (fcross) Selection
      2. 2.10.2 RCOMP Selection
      3. 2.10.3 CCOMP Selection
      4. 2.10.4 CHF Selection
    11. 2.11 MOSFET selection
  5. 3Implementation Results
  6. 4Small Signal Frequency Modeling
    1. 4.1 Boost Regulator Modulator Modeling
    2. 4.2 Compensation Modeling
    3. 4.3 Open Loop Modeling
  7. 5Resources

How to Design a Boost Converter Using LM5123

The LM5123 device is a wide input range, synchronous boost controller with envelope tracking capability. The device also integrates several features to meet system design requirements including precision enable, programmable UVLO, programmable soft-start, programmable switching frequency and adjustable control loop compensation. This application note details how to design a boost controller with a dynamically programmable output voltage. The results of this design are measured on the LM5123EVM-BST evaluation module and the results are presented in LM5123EVM-BST User's Guide. The basic concept and operation of a boost converter can be found in Understanding Boost Power Stages in Switchmode Power Supplies.