SLVAE22A July   2018  – March 2019 TPS54334 , TPS65251 , TPS65251-1 , TPS65251-2 , TPS65251-3 , TPS652510 , TPS65261 , TPS65263 , TPS65263-1Q1 , TPS65263-Q1 , TPS65265 , TPS65266 , TPS65266-1 , TPS65270 , TPS65273V , TPS65276V , TPS65279 , TPS65279V

 

  1.   Power Stage Gain and Slope Compensation Measurement in PCM (Peak Current Mode) BUCK Converter
    1.     Trademarks
    2. 1 Introduction
    3. 2 Unified PCM BUCK Converter
    4. 3 Power Stage Gain Measurement
      1. 3.1 Simplified Small Signal Model for Power Stage Gain
      2. 3.2 Power Stage Gain Measurement Method
    5. 4 Slope Compensation Measurement
      1. 4.1 Relationship Between VCOMP and Se
      2. 4.2 Slope Compensation Measurement Method
    6. 5 Measurement Results Verification
      1. 5.1 TPS65261 Measured GM-PS and Se
      2. 5.2 Measured Bode Plot vs. Calculated Bode Plot
    7. 6 Summary
    8. 7 References
  2.   Revision History

3.1 Simplified Small Signal Model for Power Stage Gain

Ignoring the inductor current ripple, the load current (iLoad) is equal to the inductor current (iL) in CCM. Figure 2 shows a simplified whole system small signal model.

Fig2.gifFigure 2. Simplified Small Signal Model for PCM BUCK Converter

Equation 2 calculates the AC small signal relationship between VCOMP and iLoad.

Equation 2. Eq2.gif

Equation 3 expresses the GM-PS.

Equation 3. Eq3.gif

They are the small signal differential data where VCOMP and iLOAD are not the directly measured data.