SNVA940 November   2021 LM5157 , LM5157-Q1 , LM51571-Q1 , LM5158 , LM5158-Q1 , LM51581 , LM51581-Q1

 

  1.   Trademarks
  2. 1LM5157 Boost Design Example
  3. 2Calculations and Component Selection
    1. 2.1  Switching Frequency
    2. 2.2  Inductor Calculation
    3. 2.3  Slope Compensation Check
    4. 2.4  Inductor Selection
    5. 2.5  Diode Selection
    6. 2.6  Output Capacitor Selection
    7. 2.7  Input Capacitor Selection
    8. 2.8  UVLO Resistor Selection
    9. 2.9  Soft-Start Capacitor Selection
    10. 2.10 Feedback Resistor Selection
    11. 2.11 Control Loop Compensation
      1. 2.11.1 Crossover Frequency (fcross) Selection
      2. 2.11.2 RCOMP Selection
      3. 2.11.3 CCOMP Selection
      4. 2.11.4 CHF Selection
    12. 2.12 Power Loss and Efficiency Estimation
  4. 3Implementation Results
  5. 4Small Signal Frequency Analysis
    1. 4.1 Boost Regulator Modulator Modeling
    2. 4.2 Compensation Modeling
    3. 4.3 Open Loop Modeling

4.3 Open Loop Modeling

These equations model the open loop transfer function of the control loop.

Table 4-3 Open Loop Modeling Equations
Simplified FormulaComprehensive Formula
Open Loop Equations
Open Loop Transfer Function
Equation 59. GUID-67ADB7D8-939B-4319-B426-F75E2E5CB6B6-low.gif
Equation 60. GUID-62FEE4F6-2B2D-4A9A-97D8-50DBBF44ADEF-low.gif
Crossover Frequency
Equation 61. GUID-20210319-CA0I-HCKJ-R66L-LCG88GWMXCL9-low.gif
Use Bode Plot