SLUAAJ0 February   2024 TPS51397A , TPS54308 , TPS54320 , TPS54350 , TPS54620 , TPS54622 , TPS54821 , TPS54824 , TPS563300 , TPS566231 , TPS566235 , TPS566238 , TPS568230 , TPS56C215 , TPS62933 , TPS62933F , TPS62933O

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Comparison of Feedback Sense Methods with Second Stage Filter
  6. 3Transfer Function Derivation of PCM Converter with Second Stage Filter and Hybrid Sense
  7. 4Overall Loop Model
  8. 5Zero and Pole Analysis
  9. 6Stability Design Method
  10. 7Design Example and Experimental Validation with TPS62933F
  11. 8Summary
  12. 9References
  13.   A Appendix

Appendix

Example to use Excel or Matlab calculate fZff

If Excel is used, first input parameters following below format.

GUID-20231017-SS0I-3NW3-BKTH-49GSBDT2TG0J-low.svg Figure A-1 Use Excel to calculate fZff Step1

Change the variable name of values A2-D2 as the values of A1-D1.

GUID-20231017-SS0I-LF9Z-NCQQ-3R079HRDGZF8-low.svg Figure A-2 Use Excel to calculate fZff Step2

Input equation in E2. Input “=” first, then copy and paste below contents:

-(5.67e15*(sqrt(3)*sqrt(C_2^3*Cff^4*L_2^3*R_1^4*(4*Cff^2*R_1^2+27*C_2*L_2))-9*C_2^2*Cff^2*L_2^2*R_1^2)^(2/3)-1.3e16*C_2*Cff^2*L_2*R_1^2)/(1.49e16*C_2*Cff*L_2*R_1*(sqrt(3)*sqrt(C_2^3*Cff^4*L_2^3*R_1^4*(4*Cff^2*R_1^2+27*C_2*L_2))-9*C_2^2*Cff^2*L_2^2*R_1^2)^(1/3))/2/3.14

Then the fZff is calculated. And we can adjust Cff to make fZff>fcross.

GUID-20231017-SS0I-BQ5C-F8VJ-CPJFTVTZPVZH-low.svg Figure A-3 Use Excel to calculate fZff Step3

If Matlab is used, the following code can be used as an example:

clc

clear

R1=5e3;

C2=47e-6;

L2=15.3e-9;

Cff=620e-12;

fZff=-(5.67e15*(sqrt(3)*sqrt(C2^3*Cff^4*L2^3*R1^4*(4*Cff^2*R1^2+27*C2*L2))-9*C2^2*Cff^2*L2^2*R1^2)^(2/3)-1.3e16*C2*Cff^2*L2*R1^2)/(1.49e16*C2*Cff*L2*R1*(sqrt(3)*sqrt(C2^3*Cff^4*L2^3*R1^4*(4*Cff^2*R1^2+27*C2*L2))-9*C2^2*Cff^2*L2^2*R1^2)^(1/3))/2/3.14