SNVA941A June   2020  – November 2022 LM5156 , LM5156-Q1 , LM51561 , LM51561-Q1 , LM51561H , LM51561H-Q1 , LM5156H , LM5156H-Q1

 

  1.   How to Design a Boost Converter Using the LM5156
  2. 1LM5156 Design Example
  3. 2Example Application
  4. 3Calculations and Component Selection
    1. 3.1  Switching Frequency
    2. 3.2  Inductor Calculation
    3. 3.3  Current Sense Resistor Calculation
      1. 3.3.1 Current Sense Resistor and Slope Compensation Resistor Selection
      2. 3.3.2 Current Sense Resistor Filter Calculation
    4. 3.4  Inductor Selection
    5. 3.5  Diode Selection
    6. 3.6  MOSFET Selection
    7. 3.7  Output Capacitor Selection
    8. 3.8  Input Capacitor Selection
    9. 3.9  UVLO Resistor Selection
    10. 3.10 Soft-Start Capacitor Selection.
    11. 3.11 Feedback Resistor Selection
    12. 3.12 Control Loop Compensation
      1. 3.12.1 Select the Loop Crossover Frequency (fCROSS)
      2. 3.12.2 Determine Required RCOMP
      3. 3.12.3 Determine Required CCOMP
      4. 3.12.4 Determine Required CHF
    13. 3.13 Efficiency Estimation
  5. 4Component Selection Summary
    1.     25
  6. 5Small-Signal Frequency Analysis
    1. 5.1 Boost Regulator Modulator Modeling
    2. 5.2 Compensation Modeling
    3. 5.3 Open-Loop Modeling
  7. 6Revision History

Boost Regulator Modulator Modeling

These equations model the plant of a peak current mode boost regulator in continuous conduction mode.

Table 5-1 Control Loop Equations
Simplified FormulaComprehensive Formula
Modulator Equations
Modulator Transfer FunctionGUID-2751CEC1-B8DF-40C8-955D-CF018AF2591D-low.gifGUID-886DC869-3631-438B-8E31-16E00C686F4F-low.gif
Modulator DC GainGUID-1EBE9A27-7723-4F25-9FB3-7123CCD2EF53-low.gif
RHP ZeroGUID-8F7CF24B-FD8E-40E4-BDF9-D8DBC06F77F7-low.gif
ESR ZeroGUID-678B21A4-11BA-4CCC-A224-AF1FB0F5B682-low.gif
Low Frequency PoleGUID-04DB039E-9BBD-4207-A117-E986B0019A4C-low.gif
Sub-Harmonic Double Pole

Not Considered

GUID-C82D95C8-C110-41EF-8C49-CECFA1FBF09E-low.gif
Quality Factor

Not Considered

GUID-07EEDA77-9C79-427C-A2B6-BB52EC8A7FC8-low.gif
Slope Compensation

Not Considered

GUID-81BDBAB8-DA9D-403F-B0C2-FA8A0E22DB65-low.gif
Sensed Rising Inductor Slope

Not Considered

GUID-24F2A05F-DBFD-4309-BCF2-83C523F86041-low.gif