SLVUCI4B february   2023  – may 2023 TPS7H5001-SP

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2System Design Theory
    1. 2.1  Switching Frequency
    2. 2.2  Leading Edge Blanking
    3. 2.3  Dead Time
    4. 2.4  Enable and UVLO
    5. 2.5  Output Voltage Programing
    6. 2.6  Soft Start
    7. 2.7  Sensing Circuit
    8. 2.8  FAULT Mode
    9. 2.9  HICCUP Mode
    10. 2.10 Slope Compensation
    11. 2.11 Output Capacitance
    12. 2.12 Compensation
  6. 3Test Results
  7. 4Bill of Materials
  8. 5Schematics
  9. 6PCB Layouts
  10. 7References
  11. 8Revision History

2.12 Compensation

Before the compensator component values can be found, the power stage transconductance was calculated as shown in Equation 13.

Equation 13. g m p s =   R C S   x   C C S   x   f S W L O U T = 1   k Ω   x   100   n F   560   n H = 179

The following equations were used to achieve the desired crossover frequency, and values used as a starting value. These values were optimized during lab testing and movement of the poles and zeros further out in frequency were determined to work better for the converter as a whole.

Equation 14. R C O M P =   2 π   x   f c   x   V O U T   x   C O U T   g m e a   x   V R E F   x   g m p s = 2 π   x   10   k H z   x   1   V   x   5   m F     1800   μ S     x   0.613   V   x   179   S = 1.590   k Ω
Equation 15. C C O M P =   V O U T   x   C O U T   I O U T     x   R C O M P = 1   V   x   5   m F 20   x   1.59   k Ω = 157   n F  
Equation 16. f e s r =   1   2 π   x   C O U T   x   E S R   =   1 2 π   x   5   m F   x     0.4   m Ω =   79.6   k H z  
Equation 17. C H F =   1   2 π   x   R c o m p   x   f e s r   =   1 2 π   x     1.59   k Ω   x   79.6   k H z =   1.26   n F