ZHCSHX8D September 2017 – October 2019 TPS50601A-SP
PRODUCTION DATA.
There are several industry techniques used to compensate DC-DC regulators. For this design, type 2B compensation is used as shown in Small Signal Model for Frequency Compensation.
First, the modulator pole, fpmod, and the RESR zero, fzmod must be calculated using Equation 17 and Equation 18. Use Equation 19 and Equation 20 to estimate a starting point for the closed loop crossover frequency fco, then the required compensation components may be derived. For this design example, fpmod is 1.16 kHz and fzmod is 80.38 kHz. Equation 19 is the geometric mean of the modulator pole and the ESR zero and Equation 20 is the geometric mean of the modulator pole and one half the switching frequency. Use a frequency near the lower of these two values as the intended crossover frequency fco. In this case Equation 19 yields 9.65 kHz and Equation 20 yields 7.61 kHz. A frequency of 7.6 kHz is chosen as the intended crossover frequency.
Now the compensation components can be calculated using Equation 10 and Equation 11. The standard values for R3 and C1 are 1.6 kΩ and 82 nF, respectively.