SLVAEJ1 January   2020 TPS25830-Q1 , TPS25830A-Q1 , TPS25831-Q1 , TPS25832-Q1 , TPS25833-Q1 , TPS25840-Q1 , TPS25842-Q1

 

  1.   Loop Characteristic Evaluation and Optimization of TPS2583x-Q1
    1. 1 Introduction
      1. 1.1 Loop Introduction of TPS2583x-Q1
    2. 2 Loop Test Method of TPS2583x-Q1
      1. 2.1 Test the Loop Characteristics Without Cable Compensation Function
      2. 2.2 Evaluating Loop Characteristics With Cable Compensation Function
    3. 3 How to improve the loop characteristic of TPS2583x-Q1
    4. 4 Summary
    5. 5 References

2.1 Test the Loop Characteristics Without Cable Compensation Function

When the cable compensation function is disabled, the frequency response analyzer can be used to measure the loop characteristics of TPS2583x-Q1, setup as shown in Figure 3. You can get its crossover frequency, phase margin and gain margin. For this test, you need to do some modifications based on the TPS25831Q1EVM:

  1. Change Rsns(R4) and Rimon(R16) to 0 Ω
  2. Remove External FET Q1
  3. Cut the wire between Vout and CSN/OUT, and add a 20 Ω resistor between it.
figure3.pngFigure 3. Setup of Loop Test

Figure 4 shows the test result. The crossover frequency is 39.25 kHz, phase margin is 44.914°, gain margin is 13.52dB.

figure4.pngFigure 4. Loop Result of TPS2583x-Q1 System Without Cable Compensation